warning cleanup.

- fix mistake with grease pencil UI (&& was intended but & used).
- use (void) rather then () across _all_ blenders code.
- a few minor edits, don't shadow stack variables in roll calculation & avoid running memset() for VBO vertex map.

source/blender/editors/interface/interface_icons.c

@@ -705,7 +705,7 @@ ListBase *UI_iconfile_list(void)
 }
 
 
-void UI_icons_free()
+void UI_icons_free(void)
 {
 	if(icongltex.id) {
 		glDeleteTextures(1, &icongltex.id);