build: add symbol for upcoming gcc 4.9's libstdc++

src/compat/glibcxx_compat.cpp

@@ -77,4 +77,11 @@ ctype<char>::_M_widen_init() const {
         }
 }
 
+void  __throw_out_of_range_fmt(const char*, ...) __attribute__((__noreturn__));
+void  __throw_out_of_range_fmt(const char* err, ...)
+{
+    // Safe and over-simplified version. Ignore the format and print it as-is.
+    __throw_out_of_range(err);
+}
+
 }// namespace std