refs.c: change resolve_ref_unsafe reading argument to be a flags field

resolve_ref_unsafe takes a boolean argument for reading (a nonexistent ref
resolves successfully for writing but not for reading).  Change this to be
a flags field instead, and pass the new constant RESOLVE_REF_READING when
we want this behaviour.

While at it, swap two of the arguments in the function to put output
arguments at the end.  As a nice side effect, this ensures that we can
catch callers that were unaware of the new API so they can be audited.

Give the wrapper functions resolve_refdup and read_ref_full the same
treatment for consistency.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/remote.c b/builtin/remote.c
index 9a4640d..42a533a 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -567,7 +567,8 @@
 	strbuf_addf(&buf, "refs/remotes/%s/", rename->old);
 	if (starts_with(refname, buf.buf)) {
 		item = string_list_append(rename->remote_branches, xstrdup(refname));
-		symref = resolve_ref_unsafe(refname, orig_sha1, 1, &flag);
+		symref = resolve_ref_unsafe(refname, RESOLVE_REF_READING,
+					    orig_sha1, &flag);
 		if (flag & REF_ISSYMREF)
 			item->util = xstrdup(symref);
 		else
@@ -703,7 +704,7 @@
 		int flag = 0;
 		unsigned char sha1[20];
 
-		read_ref_full(item->string, sha1, 1, &flag);
+		read_ref_full(item->string, RESOLVE_REF_READING, sha1, &flag);
 		if (!(flag & REF_ISSYMREF))
 			continue;
 		if (delete_ref(item->string, NULL, REF_NODEREF))