Merge branch 'maint' into master.

Merge branch 'maint' into master.

* m4/regex.m4: Bump serial number by some notches, for good
measure.  Prefer the deprecation message from maint over that
from master.
* m4/python.m4: Bump serial number.
* tests/Makefile.am (canon6.log): Depend on `libtool-macros.log'.
(canon7.log): Likewise.
(extradep2.log): Likewise.
(ar-lib4.log): Likewise.
(ar-lib6a.log): Likewise.
(ar-lib6b.log): Likewise.
(vartypo2): Likewise.
(posixsubst-ltlibraries.log): Likewise.
* tests/defs: Adjust the path of the included `get.sh' scripts
generated by `libtool-macros.test' and `gettext-macros.test'.
* aclocal.m4: Delete, it's auto-generated now.
* configure: Likewise.
* Makefile.in: Likewise.
* doc/Makefile.in: Likewise.
* m4/Makefile.in: Likewise.
* tests/Makefile.in: Likewise.
* lib/Makefile.in: Likewise.
* lib/am/Makefile.in: Likewise.
* lib/Automake/Makefile.in: Likewise.
* lib/Automake/tests/Makefile.in: Likewise.
* .gitignore: Correctly ignored the autogenerated files
that are not committed anymore.