add sdl2 config and .pc file

deps/sdl2/bin/sdl2-config

@@ -0,0 +1,60 @@
+#!/bin/sh
+
+prefix="$(cd "${0%/*}/.."; pwd)"
+exec_prefix=${prefix}
+exec_prefix_set=no
+libdir=${exec_prefix}/lib
+
+#usage="\
+#Usage: $0 [--prefix[=DIR]] [--exec-prefix[=DIR]] [--version] [--cflags] [--libs]"
+usage="\
+Usage: $0 [--prefix[=DIR]] [--exec-prefix[=DIR]] [--version] [--cflags] [--libs] [--static-libs]"
+
+if test $# -eq 0; then
+      echo "${usage}" 1>&2
+      exit 1
+fi
+
+while test $# -gt 0; do
+  case "$1" in
+  -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
+  *) optarg= ;;
+  esac
+
+  case $1 in
+    --prefix=*)
+      prefix=$optarg
+      if test $exec_prefix_set = no ; then
+        exec_prefix=$optarg
+      fi
+      ;;
+    --prefix)
+      echo $prefix
+      ;;
+    --exec-prefix=*)
+      exec_prefix=$optarg
+      exec_prefix_set=yes
+      ;;
+    --exec-prefix)
+      echo $exec_prefix
+      ;;
+    --version)
+      echo 2.0.12
+      ;;
+    --cflags)
+      echo -I${prefix}/include/SDL2  -D_THREAD_SAFE
+      ;;
+#    --libs)
+#      echo -L${exec_prefix}/lib  -lSDL2 
+#      ;;
+#    --static-libs)
+    --libs|--static-libs)
+      echo -L${libdir} -lSDL2 -framework AudioToolbox -framework AVFoundation -framework Carbon -framework Cocoa -framework CoreAudio -framework CoreFoundation -framework CoreVideo -framework ForceFeedback -framework Foundation -framework IOKit
+      ;;
+    *)
+      echo "${usage}" 1>&2
+      exit 1
+      ;;
+  esac
+  shift
+done

deps/sdl2/lib/pkgconfig/sdl2.pc

@@ -0,0 +1,15 @@
+# sdl pkg-config source file
+
+prefix=
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${prefix}/include
+
+Name: sdl2
+Description: Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer.
+Version: 2.0.12
+Requires:
+Conflicts:
+Libs: -L${libdir}  -lSDL2 
+Libs.private: -L${libdir} -lSDL2 -framework AudioToolbox -framework AVFoundation -framework Carbon -framework Cocoa -framework CoreAudio -framework CoreFoundation -framework CoreVideo -framework ForceFeedback -framework Foundation -framework IOKit
+Cflags: -I${includedir}/SDL2  -D_THREAD_SAFE