* Added #define _USE_MATH_DEFINES

in some files to get Blender to compile again on msvc. Without that, it didn't found M_PI.

source/blender/blenkernel/intern/unit.c

@@ -20,6 +20,7 @@
  *
  * ***** END GPL LICENSE BLOCK *****
  */
+#define _USE_MATH_DEFINES
 
 #include <stdlib.h>
 #include <stdio.h>

source/blender/makesrna/intern/rna_brush.c

@@ -21,6 +21,7 @@
  *
  * ***** END GPL LICENSE BLOCK *****
  */
+ #define _USE_MATH_DEFINES
 
 #include <stdlib.h>
 #include <math.h>

source/blender/makesrna/intern/rna_fcurve.c

@@ -22,6 +22,8 @@
  * ***** END GPL LICENSE BLOCK *****
  */
 
+ #define _USE_MATH_DEFINES
+ 
 #include <stdlib.h>
 #include <math.h>