gitweb: add `status` headers to git_feed() responses.

The git_feed() method was not setting a `Status` header unless it was
responding to an If-Modified-Since request with `304 Not Modified`.
Now, when it is serving successful responses, it sets status to `200
OK`.

Signed-off-by: W Trevor King <wking@drexel.edu>
Acked-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -7841,11 +7841,13 @@ sub git_feed {
 		print $cgi->header(
 			-type => $content_type,
 			-charset => 'utf-8',
-			-last_modified => $latest_date{'rfc2822'});
+			-last_modified => $latest_date{'rfc2822'},
+			-status => '200 OK');
 	} else {
 		print $cgi->header(
 			-type => $content_type,
-			-charset => 'utf-8');
+			-charset => 'utf-8',
+			-status => '200 OK');
 	}
 
 	# Optimization: skip generating the body if client asks only