Tighten dependency on libapr0, to get the version that links to
libdb4.4. This is probably a bug with the apr shlibs file, but this
workaround will do until it's addressed in apache2.
Who knows, they may not even agree about the db version being part of
the ABI. After all, if it _really_ is part of the ABI, they should
have renamed libapr0 when they moved to db4.4.