gqt -- gitolite quick (re-)test

sometimes I want to quickly test a few lines of change within the context of
a currently-running/just-ran test, *without* doing the rollback etc.

Here's how you do that now:

  - in your source tree, make the change and then run:
        cp -a src hooks contrib/adc /some/tmp/place
  - go to the tester userid and re-run your tests like so:
        GQT=/some/tmp/place ./test-driver.sh
    it'll rollback as normal then overwrite src and hooks from $GQT

Also, there's now a "dbg" sub that can be used for quick printf-style
debugging.

src/gitolite.pm

@@ -57,6 +57,12 @@ sub wrap_open {
     return $fh;
 }
 
+sub dbg {
+    for my $i (@_) {
+        print STDERR "DBG: $i\n";
+    }
+}
+
 sub log_it {
     my ($ip, $logmsg);
     open my $log_fh, ">>", $ENV{GL_LOG} or die "open log failed: $!\n";