Test Inputs to make program:

make -n -f INPUT/GNUmakefile.make USEROPT=BWGC VPATH=../make
make -n -f INPUT/GNUmakefile.gs USEROPT=BWGC VPATH=../gs
make -n -f INPUT/GNUmakefile.perl USEROPT=BWGC VPATH=../perl

Note that the VPATH must be modified to correspond the the appropriate
directory.