Log Message:
bareos: Fix build on SunOS.

Remove ONLY_FOR_PLATFORM.  We don't deliberately break platforms just because
they haven't been tested.  Fix PKG_SHELL to use ${SH}, there is no guarantee
that /bin/sh is the right shell on all platforms.

There are some other cleanups necessary in this package (e.g. bsd.pkg.mk is
included way too early), but they can wait for the 22.0.1 update.