Revert "[CMAKE] Fixed emcc warnings about SDL & OPENGL_LIBRARIES being nil"

This reverts commit 8d59fcd7f1deb470bbe7caec0f5b92b6be3bfd36.

CMakeLists.txt

@@ -145,8 +145,6 @@ set(OXYGINE_LIBRARY_DIRS
 
 if (FORCE_GLES)
 	set(OPENGL_LIBRARIES libGLESv2.lib)
-else ()
-   set(OPENGL_LIBRARIES  "")
 endif(FORCE_GLES)
 
 
@@ -161,10 +159,8 @@ set(CORE_LIBS
 
 
 if (OX_USE_SDL2)
-   if(!EMSCRIPTEN)
-	     set(CORE_LIBS ${CORE_LIBS}
-		      SDL2main SDL2)
-   endif(!EMSCRIPTEN)
+	set(CORE_LIBS ${CORE_LIBS}
+		SDL2main SDL2)
 	set(OXYGINE_INCLUDE_DIRS ${OXYGINE_INCLUDE_DIRS} ${SDL2_INCLUDE_DIRS})
 endif(OX_USE_SDL2)