Fix for previous commit - since it's for non-debug unused vars, name it UNUSED_VARS_NDEBUG.

This commit was proudly crafted by the Commit Rate Raising Committee!

source/blender/blenlib/BLI_utildefines.h

@@ -590,9 +590,9 @@ extern "C" {
 
 /* for debug-only variables */
 #ifndef NDEBUG
-#  define UNUSED_VARS_DEBUG(...)
+#  define UNUSED_VARS_NDEBUG(...)
 #else
-#  define UNUSED_VARS_DEBUG UNUSED_VARS
+#  define UNUSED_VARS_NDEBUG UNUSED_VARS
 #endif
 
 /*little macro so inline keyword works*/