Better patch for missing M_PI constants

include/math.h

@@ -1,5 +1,14 @@
 #include <openlibm_math.h>
 
 // Included to fix mesa issues
-#define M_PI_2 (M_PI/2.0)
-#define M_PI_4 (M_PI/4.0)
+#ifndef M_PI
+#define	M_PI		3.14159265358979323846	/* pi */
+#endif
+
+#ifndef M_PI_2
+#define	M_PI_2		1.57079632679489661923	/* pi/2 */
+#endif
+
+#ifndef M_PI_4
+#define	M_PI_4		0.78539816339744830962	/* pi/4 */
+#endif