[parted-devel] make "make distcheck" work once again

[Jim Meyering]

Joel Granados mentioned (thanks, Joel) that "make distcheck" was failing
due to the taint-distcheck test's abuse (srcdir name containing a space).
There were problems with the tests scripts, and I fixed those, but there
also appears to be a problem with libtool-generated scripts, so rather
than delving into that, I've simply disabled the taint-distcheck rule.

I've also taken the opportunity to update to latest version of gnulib.