patch 9.1.0884: gcc warns about uninitialized variable

Problem:  gcc warns about uninitialized variable in vim_strnicmp_asc()
Solution: initialize variable to 1
          (John Marriott)

closes: #16108

Signed-off-by: John Marriott <basilisk@internode.on.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/strings.c

@@ -597,7 +597,7 @@ vim_strnicmp(char *s1, char *s2, size_t len)
     int
 vim_strnicmp_asc(char *s1, char *s2, size_t len)
 {
-    int                i;
+    int                i = 0;
     int                save_cmp_flags = cmp_flags;
 
     cmp_flags |= CMP_KEEPASCII;		// compare by ASCII value, ignoring locale