patch 8.0.0452: some macros are in lower case

Problem:    Some macros are in lower case.
Solution:   Make a few more macros upper case.
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index 13f5065..20ef186 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -6351,12 +6351,12 @@
 		break;
 
 	    case NFA_WHITE:	/*  \s	*/
-		result = vim_iswhite(curc);
+		result = VIM_ISWHITE(curc);
 		ADD_STATE_IF_MATCH(t->state);
 		break;
 
 	    case NFA_NWHITE:	/*  \S	*/
-		result = curc != NUL && !vim_iswhite(curc);
+		result = curc != NUL && !VIM_ISWHITE(curc);
 		ADD_STATE_IF_MATCH(t->state);
 		break;