Rename sha1_array to oid_array

Since this structure handles an array of object IDs, rename it to struct
oid_array.  Also rename the accessor functions and the initialization
constant.

This commit was produced mechanically by providing non-Documentation
files to the following Perl one-liners:

    perl -pi -E 's/struct sha1_array/struct oid_array/g'
    perl -pi -E 's/\bsha1_array_/oid_array_/g'
    perl -pi -E 's/SHA1_ARRAY_INIT/OID_ARRAY_INIT/g'

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

remote-curl.c

@@ -163,7 +163,7 @@ struct discovery {
 	char *buf;
 	size_t len;
 	struct ref *refs;
-	struct sha1_array shallow;
+	struct oid_array shallow;
 	unsigned proto_git : 1;
 };
 static struct discovery *last_discovery;