Fix --with-gnustepdir
Commit
acc868d91d1457770f3b85c9636d7370721bf1a9 tried to change
--with-appspath to --with-gnustepdir, but either it wasn't done
correctly (and no one noticed) or old versions of AC_ARG_WITH worked
completely differently (and in an extremely odd way) because the option
remained --with-appspath and just the help text was changed. Then commit
bde572f67311f156f4ec4469e2ea4f16d7b1130a, which claims to have been
fixing some sort of issue with path assignment, broke it completely (i
guess) because the author there trusted the help text.
This completes the change from commit
acc868d91d1457770f3b85c9636d7370721bf1a9 that makes the option really be
--with-gnustepdir.
Signed-off-by: Brad Jorsch <anomie@users.sourceforge.net>