Random makefile cleanup prior to bmake import

Random makefile cleanup prior to bmake import

Bmake does not like to encounter "exit 0" or "exit 1".  It fails using the
exec command.  Replace instances of "exit 1" with /usr/bin/false.  There
was one instance of "exit 0" but it was at the end the target and thus
unnecessary.

The groff/tmac makefile was improved by providing a cd command for
every installed file.

Finally, one of the test makefiles was missing a single quote in one of
the targets.