Use new HASHMAP_INIT macro to simplify hashmap initialization

Now that hashamp has lazy initialization and a HASHMAP_INIT macro,
hashmaps allocated on the stack can be initialized without a call to
hashmap_init() and in some cases makes the code a bit shorter.  Convert
some callsites over to take advantage of this.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/range-diff.c b/range-diff.c
index befeeca..b9950f1 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -232,11 +232,9 @@ static int patch_util_cmp(const void *dummy, const struct patch_util *a,
 
 static void find_exact_matches(struct string_list *a, struct string_list *b)
 {
-	struct hashmap map;
+	struct hashmap map = HASHMAP_INIT((hashmap_cmp_fn)patch_util_cmp, NULL);
 	int i;
 
-	hashmap_init(&map, (hashmap_cmp_fn)patch_util_cmp, NULL, 0);
-
 	/* First, add the patches of a to a hash map */
 	for (i = 0; i < a->nr; i++) {
 		struct patch_util *util = a->items[i].util;