Guard GOOGLE_PREDICT_TRUE|FALS with #ifndef to avoid collision with other google…

Guard GOOGLE_PREDICT_TRUE|FALS with #ifndef to avoid collision with other google opensource projects like protobuf.

src/glog/logging.h.in

@@ -129,15 +129,28 @@ typedef unsigned __int64 uint64;
 #ifndef GOOGLE_PREDICT_BRANCH_NOT_TAKEN
 #if @ac_cv_have___builtin_expect@
 #define GOOGLE_PREDICT_BRANCH_NOT_TAKEN(x) (__builtin_expect(x, 0))
-#define GOOGLE_PREDICT_FALSE(x) (__builtin_expect(x, 0))
-#define GOOGLE_PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
 #else
 #define GOOGLE_PREDICT_BRANCH_NOT_TAKEN(x) x
+#endif
+#endif
+
+#ifndef GOOGLE_PREDICT_FALSE
+#if @ac_cv_have___builtin_expect@
+#define GOOGLE_PREDICT_FALSE(x) (__builtin_expect(x, 0))
+#else
 #define GOOGLE_PREDICT_FALSE(x) x
+#endif
+#endif
+
+#ifndef GOOGLE_PREDICT_TRUE
+#if @ac_cv_have___builtin_expect@
+#define GOOGLE_PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
+#else
 #define GOOGLE_PREDICT_TRUE(x) x
 #endif
 #endif
 
+
 // Make a bunch of macros for logging.  The way to log things is to stream
 // things to LOG(<a particular severity level>).  E.g.,
 //