dist: deprecated shar and tar+compress formats

dist: deprecated shar and tar+compress formats

See also discussion about automake wishlist bug#13324.

* lib/Automake/Options.pm: Give proper warnings in the 'obsolete'
category if the 'dist-shar' or 'dist-tarZ' options are used.
* lib/distdir.am: When the 'dist-tarZ' or 'dist-shar' targets are
invoked, make them give a non-fatal warning.
* doc/automake.texi: Report the new deprecations.
* t/dist-shar.sh: New test.
* t/dist-tarZ.sh: Likewise.
* t/lzma.sh: While at it, rename ...
* t/dist-lzma.sh: ... like this, and tweak it to keep more in
sync with the new tests.
* t/dist-formats.tap: Remove references to deprecated formats.
* t/list-of-tests.mk: Adjust.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>