Don't build with uClibc-ng. It's totally unsupported as several functions
are missing.
Make the musl libc support conditional.
Fix hash with make check FIXUP=1. Apparently I based the Makefile off of
libedit and forgot to fix the hash.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Fixes: 856ea2bad3 ("libcxx: Add package")