orca/orca.pl.in: work around pod2man error.

$ pod2man --stderr orca/orca.pl.in >/dev/null
orca/orca.pl.in around line 2283: You can't have =items (as at line 2288) unless the first thing after the =over is an =item
Delete svn:keywords: HeadURL and LastChanged{By,Date,Revision}.

Since these keywords have to meaning to git, delete them since they
will never be expanded.