Fix warnings reported by MSVC

Mainly it's related on a bad practice in SDL to force-define __SSE__
and __SSE2__ flags which generates quite some warnings and causes too
much noise.

There are some other warnings fixed. Should be no functional changes.

NeXyon, please check the changes in audaspace :)

source/blender/python/intern/bpy_app_sdl.c

@@ -30,7 +30,18 @@
 #include "bpy_app_sdl.h"
 
 #ifdef WITH_SDL
+/* SDL force defines __SSE__ and __SSE2__ flags, which generates warnings
+ * because we pass those defines via command line as well. For until there's
+ * proper ifndef added to SDL headers we ignore the redefinition warning.
+ */
+#  ifdef _MSC_VER
+#    pragma warning(push)
+#    pragma warning(disable : 4005)
+#  endif
 #  include "SDL.h"
+#  ifdef _MSC_VER
+#    pragma warning(pop)
+#  endif
 #  ifdef WITH_SDL_DYNLOAD
 #    include "sdlew.h"
 #  endif