[MERGE REQUEST] merge patches for AM_TESTSUITE_ENVIRONMENT into maint

[Stefano Lattarini]

Hello automakers.

I think that the patches introducing support for AM_TESTSUITE_ENVIRONMENT
should be merged into maint, as they'd make a nice addition for 1.11.2.
I've verified that almost all these patches are based off of maint, and
the few that aren't (e.g., `v1.11-867-g1e005df') are just testsuite
additions (and could probably be cherry-picked anyway, but I'm not sure
whther that would be worthwhile).  My proposal is to push the last
relevant commit (should be `v1.11-351-g3e334a2') to a new public branch
'am-tests-environment', tie up the last loose ends (if any), and finally
merge that branch into maint.  Objections?

Regards,
  Stefano