Merge branch 'maint'

Merge branch 'maint'

* maint:
  tests: more information about Lex and Yacc programs
  lint: fix spurious failure for 'sc_rm_minus_f' syntax check
  maint: bump version 1.13.1a -> 1.13.2a
  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
  plans: we are not going to remove AM_PROG_MKDIR_P in Automake 1.14
  NEWS: we are not going to remove AM_PROG_MKDIR_P in Automake 1.14
  init.m4: add probe to check "rm -f" without args work

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