cmake: Detect features at compile time

Instead of relying on manually passed down flags from CMake,
we now have ppsspp_config.h file to create the platform defines for us.
This improves support for multiplatform builds (such as iOS).

cmake/Toolchains/ios.cmake

@@ -14,7 +14,6 @@ set(MOBILE_DEVICE ON)
 set(USING_GLES2 ON)
 set(IPHONEOS_DEPLOYMENT_TARGET 6.0)
 add_definitions(
-  -DIOS
   -DGL_ETC1_RGB8_OES=0
   -U__STRICT_ANSI__
 )

cmake/Toolchains/raspberry.armv6.cmake

@@ -13,7 +13,7 @@ link_directories(
 )
 
 add_definitions(
-  -DRPI
+  -DPPSSPP_PLATFORM_RPI=1
 )
 
 set(ARCH_FLAGS "-mfpu=vfp -march=armv6j -mfloat-abi=hard")

cmake/Toolchains/raspberry.armv7.cmake

@@ -13,7 +13,7 @@ link_directories(
 )
 
 add_definitions(
-  -DRPI
+  -DPPSSPP_PLATFORM_RPI=1
   -U__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2
 )