Merge "Add a pre-C++11 constexpr compatibility macro."

include/utils/Compat.h

@@ -43,6 +43,17 @@ static inline ssize_t pread64(int fd, void* buf, size_t nbytes, off64_t offset)
 #  define ZD_TYPE long
 #endif
 
+/*
+ * Needed for cases where something should be constexpr if possible, but not
+ * being constexpr is fine if in pre-C++11 code (such as a const static float
+ * member variable).
+ */
+#if __cplusplus >= 201103L
+#define CONSTEXPR constexpr
+#else
+#define CONSTEXPR
+#endif
+
 /*
  * TEMP_FAILURE_RETRY is defined by some, but not all, versions of
  * <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's