replaced all local definitions of PI by a single one

For code maintainability, it is better to have a single definition of the
constant than many ones dispatched in many places. In addition, we try to
count on the constant M_PI that can be defined by the header <math.h> if
possible because it may have the best accuracy for the platform.

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

wrlib/scale.c

@@ -27,11 +27,6 @@
 #include <string.h>
 #include <X11/Xlib.h>
 #include <math.h>
-
-#ifndef PI
-#define PI 3.14159265358979323846
-#endif
-
 #include <assert.h>
 
 #include "wraster.h"
@@ -200,7 +195,7 @@ static double sinc(double x)
 	 * The goal was to avoid a Divide-by-0 error, now we also
 	 * avoid a +/-inf result too
 	 */
-	x *= PI;
+	x *= WM_PI;
 	if (x > 1.0E-9)
 		return (sin(x) / x);
 	return (1.0);