Ensure CMake finds SDL 2.0

CMake 2.8 doesn't search /usr/include/SDL2, which is the include directory
for SDL 2.x on Ubuntu Linux (and possibly others). This results in SDL 1.2
headers being found when WITH_SDL_DYNLOAD=OFF, and our shipped SDL 2.0
headers when WITH_SDL_DYNLOAD=ON. This patch ensures that in both
cases the correct SDL headers are used.

Reviewers: sergey, campbellbarton

Projects: #bf_blender

Differential Revision: https://developer.blender.org/D1112

CMakeLists.txt

@@ -838,17 +838,21 @@ if(UNIX AND NOT APPLE)
 
 	if(WITH_SDL)
 		if(WITH_SDL_DYNLOAD)
-			set(SDLMAIN_LIBRARY)
 			set(SDL_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/extern/sdlew/include/SDL2")
 			set(SDL_LIBRARY)
-			set(SDL_LIBRARY_TEMP)
 		else()
-			find_package_wrapper(SDL)
+			find_package_wrapper(SDL2)
+			if(SDL2_FOUND)
+				# Use same names for both versions of SDL until we move to 2.x.
+				set(SDL_INCLUDE_DIR "${SDL2_INCLUDE_DIR}")
+				set(SDL_LIBRARY "${SDL2_LIBRARY}")
+				set(SDL_FOUND "${SDL2_FOUND}")
+			else()
+				find_package_wrapper(SDL)
+			endif()
 			mark_as_advanced(
-				SDLMAIN_LIBRARY
 				SDL_INCLUDE_DIR
 				SDL_LIBRARY
-				SDL_LIBRARY_TEMP
 			)
 			# unset(SDLMAIN_LIBRARY CACHE)
 			if(NOT SDL_FOUND)