patch 8.0.1768: SET_NO_HLSEARCH() used in a wrong way

Problem:    SET_NO_HLSEARCH() used in a wrong way.
Solution:   Make it a function. (suggested by Dominique Pelle,
            closes #2850)
diff --git a/src/screen.c b/src/screen.c
index d1f17b5..06dc304 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -7945,7 +7945,7 @@
 		{
 		    /* don't free regprog in the match list, it's a copy */
 		    vim_regfree(shl->rm.regprog);
-		    SET_NO_HLSEARCH(TRUE);
+		    set_no_hlsearch(TRUE);
 		}
 		shl->rm.regprog = NULL;
 		shl->lnum = 0;