Merge branch 'branch-1.13.2' into maint

Merge branch 'branch-1.13.2' into maint

That branch is for the "emergency" bug-fixing release 1.13.2.

* branch-1.13.2:
  maint: update copyright in files generated by automake and aclocal
  tests: avoid a spurious failure when running inside Emacs
  tests: make two new test executable
  m4: rename an m4 file to a more appropriate name
  NEWS: update w.r.t. recent documentation fixes
  compat: reinstate AM_CONFIG_HEADER and AM_PROG_CC_STDC
  docs: parallel-tests is no longer experimental
  docs: serial-tests are not deprecated, just discouraged
  NEWS: we are not going to remove AM_PROG_MKDIR_P in Automake 1.14

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