gitweb: Output valid utf8 in git_blame_common('data')

Otherwise when javascript-actions are enabled gitweb shown broken
author names in the tooltips on blame pages ('blame_incremental'
view).

Signed-off-by: Jürgen Kreileder <jk@blackdown.de>
Acked-by: Jakub Narębski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/gitweb.perl

@@ -6108,7 +6108,9 @@ sub git_blame_common {
 			-type=>"text/plain", -charset => "utf-8",
 			-status=> "200 OK");
 		local $| = 1; # output autoflush
-		print while <$fd>;
+		while (my $line = <$fd>) {
+			print to_utf8($line);
+		}
 		close $fd
 			or print "ERROR $!\n";