amdgpu: make libdir work on stock Linux

BUG=b:145747113
TEST=emerge-grunt minigbm

Cq-Depend: chromium:1967711
Change-Id: I10e721ffcbe8e36551269cf54e981be411389eaf
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/1967731
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Commit-Queue: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
diff --git a/util.h b/util.h
index e4e1399..8f8bb0d 100644
--- a/util.h
+++ b/util.h
@@ -13,5 +13,7 @@
 #define ALIGN(A, B) (((A) + (B)-1) & ~((B)-1))
 #define IS_ALIGNED(A, B) (ALIGN((A), (B)) == (A))
 #define DIV_ROUND_UP(n, d) (((n) + (d)-1) / (d))
+#define STRINGIZE_NO_EXPANSION(x) #x
+#define STRINGIZE(x) STRINGIZE_NO_EXPANSION(x)
 
 #endif