Handle an edge-case where lang/gawk is installed prior to any autoconf*
ports, which then results in an implicit dependency on gawk, with the
obvious bad things happening should gawk be later removed.
Note that because this is an edge case, which most folks will not run
into, and because it doesn't change the default package, I am not
bumping PORTREVISION as suggested in the original patch.
Who: matthias <dot> andree <at> gmx <dot> de