patch 9.0.1427: warning for uninitialized variable

Problem:    Warning for uninitialized variable. (Tony Mechelynck)
Solution:   Add #ifdef.

Author: brammool

src/regexp_nfa.c

@@ -6678,7 +6678,9 @@ nfa_regmatch(
 		int subidx;
 		int bytelen;
 
-		if (t->state->c <= NFA_BACKREF9)
+#ifdef FEAT_SYN_HL
+		if (t->state->c >= NFA_BACKREF1 && t->state->c <= NFA_BACKREF9)
+#endif
 		{
 		    subidx = t->state->c - NFA_BACKREF1 + 1;
 		    result = match_backref(&t->subs.norm, subidx, &bytelen);

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1427,
 /**/
     1426,
 /**/