update-ref: fix type of update_flags variable to match its usage

The ref_transaction_*() family of functions expect a flags parameter
which is of type unsigned int.  Make the update_flags variable, which
is passed as that parameter, be of the same type.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

builtin/update-ref.c

@@ -14,7 +14,7 @@ static const char * const git_update_ref_usage[] = {
 };
 
 static char line_termination = '\n';
-static int update_flags;
+static unsigned int update_flags;
 static unsigned create_reflog_flag;
 static const char *msg;