Merge branch 'maint'

Merge branch 'maint'

* maint:
  tests: minor reorganization of few tests
  fixup: adjust t/list-of-tests.mk for renamed/added tests
  subdirs: enhance coverage, tweak and rename few tests
  sync: update files from upstream with "make fetch"
  py-compile: consistently quote 'like this', not `like this'.
  docs: recursive make considered harmful
  docs: clean rules are not run in reverse order of build rules anymore
  silent: new $(AM_V_P) variable, tell if we're running in silent mode
  refactor: silent rules handling (a little)
  refactor: &define_verbose_var: accept a third optional argument

+ Extra non-trivial edits:

These are due to the fact that support for silent rules is enabled
unconditionally these days (since commit 'v1.12-34-g14141f2' of
2012-05-01, "silent rules: support for them is always active now").

* automake.in: In the new silent related code, do not ever check
whether the 'silent-rules' option is active; just assume support
for silent rules is enabled.
* t/silent-obsolescent-warns.sh: Remove as obsolete.
* t/list-of-tests.mk: Adjust.

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