Added a single SDL_LEAN_AND_MEAN define to turn on minimal SDL builds

Protected more code with #ifdefs to reduce the size of minimal shared library builds

src/render/SDL_yuv_sw.c

@@ -22,6 +22,8 @@
 
 /* This is the software implementation of the YUV texture support */
 
+#if SDL_HAVE_YUV
+
 #include "SDL_assert.h"
 
 #include "SDL_yuv_sw_c.h"
@@ -411,4 +413,6 @@ SDL_SW_DestroyYUVTexture(SDL_SW_YUVTexture * swdata)
     }
 }
 
+#endif /* SDL_HAVE_YUV */
+
 /* vi: set ts=4 sw=4 expandtab: */