Patch #8461, by Rob Hausauer

This unifies all usage of FTOCHAR, putting it in utildefines.h
Submitter did several interesting tests for speed, check it here:
http://projects.blender.org/tracker/?func=detail&atid=127&aid=8461&group_id=9

source/blender/gpu/intern/gpu_extensions.c

@@ -40,6 +40,7 @@
 
 #include "BKE_image.h"
 #include "BKE_global.h"
+#include "BKE_utildefines.h"
 
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
@@ -154,7 +155,6 @@ struct GPUTexture {
 	int depth;				/* is a depth texture? */
 };
 
-#define FTOCHAR(val) val<=0.0f?0: (val>=1.0f?255: (char)(255.0f*val))
 static unsigned char *GPU_texture_convert_pixels(int length, float *fpixels)
 {
 	unsigned char *pixels, *p;