tmp-dir option doesn't work in InitDB.pl

copied from http://bugs.musicbrainz.org/ticket/5169

--tmp-dir= is treated an unknown option when passed to IinitDB.pl script.

Here is the code snip:

my @opts = "--ignore-errors";
push @opts, "--fix-broken-utf8" if ($fFixUTF8);
system($^X, "$FindBin::Bin/MBImport.pl", @opts, @$import);

"--tmp-dir=" should be pushed too and "tmp-dir|t=s" should be declared inside GetOptions() as well