Add macro definitions for clang/llvm.

b/23238405
b/23793209

Change-Id: I62d1a167eebfb266e846b1de7f23873f1dfdab56
(cherry picked from commit 5859ae22db0a2d16af3e3ca19d582de37daf5eb6)
diff --git a/libFLAC/include/private/macros.h b/libFLAC/include/private/macros.h
index b72b69b..fd48a7f 100644
--- a/libFLAC/include/private/macros.h
+++ b/libFLAC/include/private/macros.h
@@ -32,7 +32,7 @@
 #ifndef FLAC__PRIVATE__MACROS_H
 #define FLAC__PRIVATE__MACROS_H
 
-#if defined(__GNUC__) && (__GNUC__ > 4 || ( __GNUC__ == 4 && __GNUC_MINOR__ >= 3))
+#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ > 4 || ( __GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
 
 #define flac_max(a,b) \
     ({ __typeof__ (a) _a = (a); \