bug#12064: distclean failure with Automake 1.12.2

[Stefano Lattarini]

Reference:
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12064>

Since I've seen no further reports of similar problems, and since we
have concluded the issue in question wasn't due to an Automake bug,
but rather to a legitimate-but-slightly-backward-incompatible change
in Automake's behaviour (change that I stupidly introduced in a minor
version, rather than in a major version as it would have been
appropriate -- sorry again about that), I'm closing this bug report.

If anybody has further observations or objections, feel free to
continue the discussion here; that should still be possible even
if the bug has been closed.

Thanks,
  Stefano