Log Message:
gcc47: don't use PCH for libstdc++ on gcc5, it causes hangs during configure.
limited to gcc5 because others do not seem to run into the same issues, to
avoid a regression for them.

disable libssp on netbsd - it conflicts with native libssp
(related: PR pkg/47213)

Use a more sane specfile for netbsd, linking against libc when building
shared.

bump gcc47 PKGREVISION
bump gcc47-libs PKGREVISION further than gcc47