Disable perl2host() processing in TAP tests

This is a preliminary step towards removing it altogether, but this lets
us double check that nothing breaks in the buildfarm before we do.

Discussion: https://postgr.es/m/0ba775a2-8aa0-0d56-d780-69427cf6f33d@dunslane.net

src/test/perl/PostgreSQL/Test/Utils.pm

@@ -311,7 +311,7 @@ The returned path uses forward slashes but has no trailing slash.
 sub perl2host
 {
 	my ($subject) = @_;
-	return $subject unless $Config{osname} eq 'msys';
+	return $subject;
 	if ($is_msys2)
 	{
 		# get absolute, windows type path