segfault on &Internals::* due to missing SvROK()

segfault on &Internals::* due to missing SvROK()

Change the &Internals::* functions that use references in their
prototypes to check if the argument is SvROK() before calling SvRV().

If the function is called as Internals::FOO() perl does this check for
us, but prototypes are bypassed on &Internals::FOO() so we still have
to check this manually.

This fixes [perl #77776], this bug was present in 5.10.x, 5.12.x, and
probably all earlier perl versions that had these functions, but I
haven't tested that.

I'm adding a new test file (t/lib/universal.t) to test universal.c
functions as part of this patch. The testing for Internal::* in t/ was
and is very sparse, but before universal.t there was no obvious place
to put these tests.

Signed-off-by: Ævar Arnfjörð Bjarmason <avar@cpan.org>