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/ex_getln.c b/src/ex_getln.c
index 01286ac..2dd8aa1 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -6027,7 +6027,7 @@
 		if (p == NULL)
 		    break;
 		++p;
-		for (i = 0; p[i] && !vim_iswhite(p[i]); ++i)
+		for (i = 0; p[i] && !VIM_ISWHITE(p[i]); ++i)
 		    if (p[i] == '\\' && p[i + 1])
 			++i;
 		STRMOVE(p, p + i);