Replace xmalloc/memset(0) pairs with xcalloc

Many call sites immediately initialize allocated memory with zero after
calling xmalloc. A single call to xcalloc can replace this two-call
sequence.
Signed-off-by: NBrandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>

builtin-merge.c

@@ -123,8 +123,7 @@ static struct strategy *get_strategy(const char *name)
 		exit(1);
 	}
 
-	ret = xmalloc(sizeof(struct strategy));
-	memset(ret, 0, sizeof(struct strategy));
+	ret = xcalloc(1, sizeof(struct strategy));
 	ret->name = xstrdup(name);
 	return ret;
 }

builtin-pack-objects.c

@@ -1369,12 +1369,10 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
 			int window, int depth, unsigned *processed)
 {
 	uint32_t i, idx = 0, count = 0;
-	unsigned int array_size = window * sizeof(struct unpacked);
 	struct unpacked *array;
 	unsigned long mem_usage = 0;
 
-	array = xmalloc(array_size);
-	memset(array, 0, array_size);
+	array = xcalloc(window, sizeof(struct unpacked));
 
 	for (;;) {
 		struct object_entry *entry = *list++;

builtin-unpack-objects.c

@@ -477,8 +477,7 @@ static void unpack_all(void)
 
 	if (!quiet)
 		progress = start_progress("Unpacking objects", nr_objects);
-	obj_list = xmalloc(nr_objects * sizeof(*obj_list));
-	memset(obj_list, 0, nr_objects * sizeof(*obj_list));
+	obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 	for (i = 0; i < nr_objects; i++) {
 		unpack_one(i);
 		display_progress(progress, i + 1);

merge-tree.c

@@ -158,9 +158,8 @@ static int same_entry(struct name_entry *a, struct name_entry *b)
 
 static struct merge_list *create_entry(unsigned stage, unsigned mode, const unsigned char *sha1, const char *path)
 {
-	struct merge_list *res = xmalloc(sizeof(*res));
+	struct merge_list *res = xcalloc(1, sizeof(*res));
 
-	memset(res, 0, sizeof(*res));
 	res->stage = stage;
 	res->path = path;
 	res->mode = mode;

remote.c

@@ -751,8 +751,7 @@ int remote_find_tracking(struct remote *remote, struct refspec *refspec)
 
 struct ref *alloc_ref(unsigned namelen)
 {
-	struct ref *ret = xmalloc(sizeof(struct ref) + namelen);
-	memset(ret, 0, sizeof(struct ref) + namelen);
+	struct ref *ret = xcalloc(1, sizeof(struct ref) + namelen);
 	return ret;
 }