Fix build error with newer gcc

http://bugs.gentoo.org/115087

--- SDL_gfxPrimitives.h
+++ SDL_gfxPrimitives.h
@@ -187,7 +187,7 @@
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus
-};
+}
 #endif
 
 #endif				/* _SDL_gfxPrimitives_h */
--- SDL_imageFilter.h
+++ SDL_imageFilter.h
@@ -186,7 +186,7 @@
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus
-};
+}
 #endif
 
 #endif				/* _SDL_imageFilter_h */