Make it possible to slim SDL down quite a bit for people who just want OpenGL

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404345

TODO

@@ -52,6 +52,7 @@
  * Make sure you can create and show a fullscreen window in one step
  * Figure out how to handle OpenGL context lost on Mac OS X (does it happen?)
  * Write automated test case for multi-draw APIs
+ * Make sure you can build SDL without the renderer to slim it down a bunch
 
 Wish list for the 1.3 development branch:
 http://bugzilla.libsdl.org/