regexp_tests is a modified copy of parrot's t/compilers/pge/p6regex/regex_tests

It seems likely we will copy this regexp_tests file from parrot
repeatedly.  It would be nice if, rather than hand editing it,
instead p6regex.t knew which tests needed to be skipped, and what
needed to be massaged.  Like parrot's pge/p6regex/01-regex.t does.