Revert "Use SDL2's own SDL2.cmake."

This reverts commit 01ac144b09.

Looks like this broke the build on some systems, because some
package managers pack SDL2Config.cmake and others pack sdl2-config.cmake
in their SDL2 development packages (for some reason, SDL2 seems
to ship both in their source, and they appear to be incompatible).

Shipping our own FindSDL2.cmake might be unclean/ugly/whatever, but
at least it works (most of the time? at least it appears to work better
than not shipping it)

neo/CMakeLists.txt

@@ -142,9 +142,8 @@ if (SDL2)
 		set(SDL2_BUILDING_LIBRARY TRUE)
 	endif()
 	find_package(SDL2 REQUIRED)
-	include_directories(${SDL2_INCLUDE_DIRS})
+	include_directories(${SDL2_INCLUDE_DIR})
-	set(SDLx_LIBRARY ${SDL2_LIBRARIES})
+	set(SDLx_LIBRARY ${SDL2_LIBRARY})
-	link_directories(${SDL2_LIBDIR})
 else()
 	# skip SDLmain
 	if(APPLE OR WIN32)

neo/sys/cmake/FindSDL2.cmake

@@ -0,0 +1,163 @@
+# Locate SDL2 library
+# This module defines
+# SDL2_LIBRARY, the name of the library to link against
+# SDL2_FOUND, if false, do not try to link to SDL2
+# SDL2_INCLUDE_DIR, where to find SDL.h
+#
+# This module responds to the the flag:
+# SDL2_BUILDING_LIBRARY
+# If this is defined, then no SDL2main will be linked in because
+# only applications need main().
+# Otherwise, it is assumed you are building an application and this
+# module will attempt to locate and set the the proper link flags
+# as part of the returned SDL2_LIBRARY variable.
+#
+# Don't forget to include SDLmain.h and SDLmain.m your project for the
+# OS X framework based version. (Other versions link to -lSDL2main which
+# this module will try to find on your behalf.) Also for OS X, this
+# module will automatically add the -framework Cocoa on your behalf.
+#
+#
+# Additional Note: If you see an empty SDL2_LIBRARY_TEMP in your configuration
+# and no SDL2_LIBRARY, it means CMake did not find your SDL2 library
+# (SDL2.dll, libsdl2.so, SDL2.framework, etc).
+# Set SDL2_LIBRARY_TEMP to point to your SDL2 library, and configure again.
+# Similarly, if you see an empty SDL2MAIN_LIBRARY, you should set this value
+# as appropriate. These values are used to generate the final SDL2_LIBRARY
+# variable, but when these values are unset, SDL2_LIBRARY does not get created.
+#
+#
+# $SDL2DIR is an environment variable that would
+# correspond to the ./configure --prefix=$SDL2DIR
+# used in building SDL2.
+# l.e.galup  9-20-02
+#
+# Modified by Eric Wing.
+# Added code to assist with automated building by using environmental variables
+# and providing a more controlled/consistent search behavior.
+# Added new modifications to recognize OS X frameworks and
+# additional Unix paths (FreeBSD, etc).
+# Also corrected the header search path to follow "proper" SDL guidelines.
+# Added a search for SDL2main which is needed by some platforms.
+# Added a search for threads which is needed by some platforms.
+# Added needed compile switches for MinGW.
+#
+# On OSX, this will prefer the Framework version (if found) over others.
+# People will have to manually change the cache values of
+# SDL2_LIBRARY to override this selection or set the CMake environment
+# CMAKE_INCLUDE_PATH to modify the search paths.
+#
+# Note that the header path has changed from SDL2/SDL.h to just SDL.h
+# This needed to change because "proper" SDL convention
+# is #include "SDL.h", not <SDL2/SDL.h>. This is done for portability
+# reasons because not all systems place things in SDL2/ (see FreeBSD).
+
+#=============================================================================
+# Copyright 2003-2009 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+SET(SDL2_SEARCH_PATHS
+	~/Library/Frameworks
+	/Library/Frameworks
+	/usr/local
+	/usr
+	/sw # Fink
+	/opt/local # DarwinPorts
+	/opt/csw # Blastwave
+	/opt
+)
+
+FIND_PATH(SDL2_INCLUDE_DIR SDL.h
+	HINTS
+	$ENV{SDL2DIR}
+	PATH_SUFFIXES include/SDL2 include
+	PATHS ${SDL2_SEARCH_PATHS}
+)
+
+FIND_LIBRARY(SDL2_LIBRARY_TEMP
+	NAMES SDL2
+	HINTS
+	$ENV{SDL2DIR}
+	PATH_SUFFIXES lib64 lib
+	PATHS ${SDL2_SEARCH_PATHS}
+)
+
+IF(NOT SDL2_BUILDING_LIBRARY)
+	IF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+		# Non-OS X framework versions expect you to also dynamically link to
+		# SDL2main. This is mainly for Windows and OS X. Other (Unix) platforms
+		# seem to provide SDL2main for compatibility even though they don't
+		# necessarily need it.
+		FIND_LIBRARY(SDL2MAIN_LIBRARY
+			NAMES SDL2main
+			HINTS
+			$ENV{SDL2DIR}
+			PATH_SUFFIXES lib64 lib
+			PATHS ${SDL2_SEARCH_PATHS}
+		)
+	ENDIF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+# SDL2 may require threads on your system.
+# The Apple build may not need an explicit flag because one of the
+# frameworks may already provide it.
+# But for non-OSX systems, I will use the CMake Threads package.
+IF(NOT APPLE)
+	FIND_PACKAGE(Threads)
+ENDIF(NOT APPLE)
+
+# MinGW needs an additional library, mwindows
+# It's total link flags should look like -lmingw32 -lSDL2main -lSDL2 -lmwindows
+# (Actually on second look, I think it only needs one of the m* libraries.)
+IF(MINGW)
+	SET(MINGW32_LIBRARY mingw32 CACHE STRING "mwindows for MinGW")
+ENDIF(MINGW)
+
+IF(SDL2_LIBRARY_TEMP)
+	# For SDL2main
+	IF(NOT SDL2_BUILDING_LIBRARY)
+		IF(SDL2MAIN_LIBRARY)
+			SET(SDL2_LIBRARY_TEMP ${SDL2MAIN_LIBRARY} ${SDL2_LIBRARY_TEMP})
+		ENDIF(SDL2MAIN_LIBRARY)
+	ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+	# For OS X, SDL2 uses Cocoa as a backend so it must link to Cocoa.
+	# CMake doesn't display the -framework Cocoa string in the UI even
+	# though it actually is there if I modify a pre-used variable.
+	# I think it has something to do with the CACHE STRING.
+	# So I use a temporary variable until the end so I can set the
+	# "real" variable in one-shot.
+	IF(APPLE)
+		SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} "-framework Cocoa")
+	ENDIF(APPLE)
+
+	# For threads, as mentioned Apple doesn't need this.
+	# In fact, there seems to be a problem if I used the Threads package
+	# and try using this line, so I'm just skipping it entirely for OS X.
+	IF(NOT APPLE)
+		SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} ${CMAKE_THREAD_LIBS_INIT})
+	ENDIF(NOT APPLE)
+
+	# For MinGW library
+	IF(MINGW)
+		SET(SDL2_LIBRARY_TEMP ${MINGW32_LIBRARY} ${SDL2_LIBRARY_TEMP})
+	ENDIF(MINGW)
+
+	# Set the final string here so the GUI reflects the final state.
+	SET(SDL2_LIBRARY ${SDL2_LIBRARY_TEMP} CACHE STRING "Where the SDL2 Library can be found")
+	# Set the temp variable to INTERNAL so it is not seen in the CMake GUI
+	SET(SDL2_LIBRARY_TEMP "${SDL2_LIBRARY_TEMP}" CACHE INTERNAL "")
+ENDIF(SDL2_LIBRARY_TEMP)
+
+INCLUDE(FindPackageHandleStandardArgs)
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDL2 REQUIRED_VARS SDL2_LIBRARY SDL2_INCLUDE_DIR)