binaries for the fixit floppy bin/ed/main.c causes a gcc warning
message about argc possibly being clobbered by longjmp or vfork.
We have threatened to ditch floppies for 8.0 but I don't want to
do quite that much rototilling yet so for now turn off -Werror while
building ed (and everything else) for the fixit floppy.
Thanks to jb for pointing out NO_WERROR.