gitweb: Use single implementation of export_ok check.

GitWeb source contains a special function that implements the
export_ok check, but validate_project still uses a separate copy
of essentially the same code.

This patch makes it use the dedicated function, thus ensuring
that all checks are done through a single code path.

Signed-off-by: Alexander Gavrilov <angavrilov@gmail.com>
Acked-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -853,8 +853,7 @@ sub validate_project {
 	my $input = shift || return undef;
 	if (!validate_pathname($input) ||
 		!(-d "$projectroot/$input") ||
-		!check_head_link("$projectroot/$input") ||
-		($export_ok && !(-e "$projectroot/$input/$export_ok")) ||
+		!check_export_ok("$projectroot/$input") ||
 		($strict_export && !project_in_list($input))) {
 		return undef;
 	} else {