Don't pass "--xhtml" to hightlight in gitweb.perl script.

The "--xhtml" option is supported only in highlight < 3.0. There is no option
to enforce (X)HTML output format compatible with both highlight < 3.0 and
highlight >= 3.0. However default output format is HTML so we don't need to
explicitly specify it.

Signed-off-by: Adam Tkac <atkac@redhat.com>
Helped-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -3468,7 +3468,7 @@ sub run_highlighter {
 	close $fd;
 	open $fd, quote_command(git_cmd(), "cat-file", "blob", $hash)." | ".
 	          quote_command($highlight_bin).
-	          " --xhtml --fragment --syntax $syntax |"
+	          " --fragment --syntax $syntax |"
 		or die_error(500, "Couldn't open file or run syntax highlighter");
 	return $fd;
 }