AIX shared libraries treat resolution of imported symbols

	AIX shared libraries treat resolution of imported symbols
different from resolution of external non-imported symbols.
Therefore, we really want to link against libdb.a at shared library
creation time.  Instead of linking on all platforms and making libdb.a
a shared library, I have chosen to only link on AIX where it will work
and not generate a problem even if the application later linksgainst
libdb.a because making libdb.a a shared library would make it harder
to distribute util/db2.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@8829 dc483132-0cff-0310-8789-dd5450dbe970