Remove hard-coded Darwin compilation flags

This broke for me on Perl 5.10 with 32-bit architecture.  I don't
think trying to second guess Perl's ccflags, etc. is robust.
use more portable minimum-perl specification
Explicitly load re::regexp_pattern for 5.10.0

Before then, it wasn't available; afterwards it was always available.
improve test labels in t/types.t
PERL-323 fix socket leaks
update Changes