Merge branch 'maint'

Merge branch 'maint'

* maint:
  cosmetics: don't make the generated Config.pm executable
  maint: reduce use of recursion in automake build system

+ Extra non-trivial extra edits follows.

* lib/Makefile.am (amdir): Deleted this definition, it is already
provided by a proper AC_SUBST in configure.ac.
(dist_am_DATA): Remove 'am/ansi2knr.am', 'am/check-html.am' and
'am/multilib.am'.
(dist_perllib_DATA): Remove 'Automake/Struct.pm'.

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