make check should check-spaces

I think we released an alpha tarball that fails make check-spaces.

nick says it's fine with him if we make 'make test' include make check-spaces.

I think a slightly better option is to make 'make dist' include it.

Is it as simple as changing "dist: check" to "dist: check check-spaces" in Makefile.am?

Turns out not to be quite that simple -- that runs check-spaces but doesn't stop if check-spaces is unhappy.