- serial-tests fix from Richard Jones' libguestfs (lgplv2+)
  (needed for automake < 1.12)
- m4_esyscmd fix from slurm project (gplv2+), needed for
  autoconf < 2.62 or so
- m4_argn from m4 sugar (gplv3+ with autoconf exceptions)
- AC_CHECK_FUNCS does not like nested macros, so outline dependend
  AC_CHECK_HEADERS
- only build c and c++ bindings for gpgme, we don't need anything
  else internally.

Change-Id: Ic65ca92119efda585ebc9acbfb7c6c2ac2585451
Reviewed-on: https://gerrit.libreoffice.org/34349Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Reviewed-by: Siegmund Gorr <siegmund.gorr@cib.de>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>