gallium: include limits.h in p_config.h

We are getting inconsistent methods for endian detection (same answer when
it works, just doesn't work on some platforms) depending on whether __GLIBC__
is defined, which of course depends on include ordering before p_config.h

Just make p_config.h include limits.h to solve this.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/gallium/include/pipe/p_config.h

@@ -46,7 +46,7 @@
 #ifndef P_CONFIG_H_
 #define P_CONFIG_H_
 
-
+#include <limits.h>
 /*
  * Compiler
  */