Merging back java-work

[Stefano Lattarini]

Hello automakers.

The java-work branch contains mostly testsuite enahcements, but also a
couple of bug fixes.  There is no point in merging such bug fixes in
master only though, since we plan to basically rewrite the whole
Automake's Java support in the next release, with heavy paradigm and
API changes (see <http://debbugs.gnu.org/9088>).

My opinion is that we should cherry-pick the bug-fixing commits from
java-work and merge them in master (so that they will be in 1.11.2),
and then merge java-work in master (mostly for the enhanced testsuite
coverage, that I hope we could reuse, at least partly, for the new
`JARS' primary).

The commits that I plan to cherry-pick for maint are the following two:
 - d76b503883525aaab6048102cbfe96bbdd9a0a85
   "java: allow both dist_JAVA and nodist_JAVA in the same Makefile.am"
 - 01dede4422493957c23b3bc7ecfe596f93a58a54
   "java: allow both JAVA and nobase_JAVA in the same Makefile.am"

I will proceed with this plan in a couple of days if there is no
objection.

Then we'll have to tackle the more thorny problem of the deprecation
of the older _JAVA primary ... but that's for when the new interface
will be ready, so no need to rush.

Regards,
  Stefano