Add PI definition for platforms that doesn't have it

SquiLu-ext/dad_utils.cpp

@@ -2,6 +2,10 @@
 #include <stdio.h>
 #include <math.h>
 
+#ifndef M_PI
+#define M_PI		3.14159265358979323846
+#endif
+
 struct lat_long_st
 {
     double latitude, longitude;