Add xor tests to test suite

Add xor tests to test suite

Subject: Re: Parser nit: possible [PATCH]

In <199706250602.CAA13384@rio.atlantic.net>, Chip Salzenberg writes:
:According to Hugo van der Sanden:
:> Can anyone explain why the parser code for OROP is different from
:> that for ANDOP? I include a patch for what I think it should be,
:> but I don't understand why all tests succeed both with and without
:> this patch.
:Because OROP is a token that's used for both "or" and "xor",
:whereas ANDOP is specific to the single keyword "and".
Ah, in that case the problem is that 'xor' appears nowhere in the
test suite. Patch below adds 4 new tests that normally succeed; my
previous (erroneous) patch causes the first of them to fail.

p5p-msgid: 199706250730.IAA06097@crypt.compulink.co.uk