Fix up Heimdal so that it can be built statically, allowing the
sun2 port to proceed beyond trying and failing to build Heimdal.
This is done by:

1) Stop pretending that libipc is a separate library, and instead
build it as part of libkrb5. The version map for libkrb5 needed
to be updated to expose the required symbols from libipc.

2) The lexer in libhx509 needs to use its own prefix, so that the
resulting library can be statically linked with a lexer which
uses the default prefix. This was hidden because libhx509's
version map file (which is only used for the shared libs) hid
away the lexer symbols. Some defines needed tweaking as well
to restore buildability.

3) Excplicitly mention all the required libraries in LDADD+= and
make sure DPADD is set to correspond. This allows static linking;
earlier this relied on shared library dependencies to have all the
libs pulled in. In the process, convert to single-line LDADD+=
and DPADD+= settings. Use Makefile.inc for the common libraries
to the extent possible.

Successfully built from scratch for i386 and sun2 several times,
and for lots of other ports as well.

Discussed with elric@ and christos@.