The "skype" binary works fine after recent update in linux compat layer when
linux-c6-pulseaudio (libpulse.so.0) is not installed (but linprocfs(5) must be
mounted into ${LINUXBASE}/proc). So:

- Unbreak net-im/skype4 for __FreeBSD_version >= 1100075.
- (temporarily) Disable PA dependency.

Also:
- Drop (indirect) PA dependencies.
- Add tcp_wrappers-libs into linux-c6-pulseaudio-libs dependencies (used by
  libpulse.so.0)
- Fix some portlint(1) warnings.

Workaround: libpulse.so.0 can be replaced with PA wrapper from
https://github.com/waterlaz/skype_oss_wrapper - then sound will work too (with
mounted devfs(5) in ${LINUXBASE}/dev).