Merge branch 'master' into ng/master

Merge branch 'master' into ng/master

* master:
  INSTALL: regen
  sync: update files from upstream with "make fetch"
  tests: tweaks and minimal improvements to t/insthook.sh
  typofix: in comments in t/extra2.sh
  tests: fix botched cross-reference in a heading comment
  compat: reinstate support for obsolete $(INCLUDES) variable
  automake: refactoring: factor out common cpp-like flags
  NEWS (mint): reflect new Automake versioning scheme
  NEWS (master): reflect new Automake versioning scheme
  Add missing '$' for variable expansion in depout.m4
  maintcheck: avoid spurious failure
  perl: perl subroutine prototypes are problematic, don't use them
  fixup: one stray reference to older versioning scheme
  preproc: enhance and extend tests
  preproc: add support for relative names in included fragments

+ Non-trivial extra changes:

* automake.in (@cpplike_flags): Use $(AM_DEFAULT_INCLUDES), not
$(DEFAULT_INCLUDES).  Do not support $(INCLUDES).
(generate_makefile): User definition of $(INCLUDES) causes a fatal
error, not a warning.

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