amd/addrlib: Fix include path for c99_compat.h

amd/addrlib: Fix include path for c99_compat.h

Without this patch mesa doesn't compile:

In file included from ../mesa-9999/src/amd/addrlib/addrinterface.cpp:39:
../mesa-9999/src/util/macros.h:29:10: fatal error: c99_compat.h: No such file or directory
 #include "c99_compat.h"
          ^~~~~~~~~~~~~~
compilation terminated.

Fixes: 15ca5ce99a80d9ebb5ef2b1aca6ea00784931de4
       ("amd/addrlib: mark returnCode as MAYBE_UNUSED in")
Signed-off-by: Mariusz Ceier <mceier+mesa-dev@gmail.com>
Acked-by: Kai Wasserbäch <kai@dev.carbon-project.org>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>