appveyor: build for GCC 5.2

appveyor.yml

@@ -11,7 +11,7 @@ before_build:
 - mingw32-make --version
 
 build_script:
-- cmd: mingw32-make.exe -C src MINGW=1 WARNINGMODE=1 NOASM=1 NOUPX=1
+- cmd: mingw32-make.exe -C src MINGW=1 WARNINGMODE=1 NOASM=1 NOUPX=1 GCC52=1
 
 on_finish:
 #- ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))

src/Makefile.cfg

@@ -7,6 +7,22 @@
 # and other things
 #
 
+ifdef GCC53
+GCC52=1
+endif
+
+ifdef GCC52
+GCC51=1
+endif
+
+ifdef GCC51
+GCC49=1
+endif
+
+ifdef GCC49
+GCC48=1
+endif
+
 ifdef GCC48
 GCC47=1
 endif