gallium: __FUNCTION__ now never be used, remove it

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Acked-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Acked-by: David Heidelberg <david.heidelberg@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19861>

src/gallium/include/pipe/p_compiler.h

@@ -77,12 +77,6 @@ typedef unsigned char boolean;
 #define FALSE false
 #endif
 
-/* XXX: Use standard `__func__` instead */
-#ifndef __FUNCTION__
-#  define __FUNCTION__ __func__
-#endif
-
-
 /* This should match linux gcc cdecl semantics everywhere, so that we
  * just codegen one calling convention on all platforms.
  */