apr-util in version 1.3.5: handle the files
${PREFIX}lib/apr-util-1/apr_dbm_db*, installed by this package when
the package option 'db4' is selected, via another PLIST_VAR, 'db4'.
The Apache Portable Run-time mission is to provide a library of
routines that allows programmers to write a program once and be
able to compile it anywhere.