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/quickfix.c b/src/quickfix.c
index e4ea401..090b046 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -2608,7 +2608,7 @@
 	{
 	    buf[i] = ' ';
 	    while (*++p != NUL)
-		if (!vim_iswhite(*p) && *p != '\n')
+		if (!VIM_ISWHITE(*p) && *p != '\n')
 		    break;
 	}
 	else