For systems that don't have libgpgme installed, the addition of the m4/gpgme.m4
file fixes the following error when running the autogen.sh script:
configure.ac:313: error: possibly undefined macro: AC_DEFINE
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
configure.ac:326: error: possibly undefined macro: AM_PATH_GPGME
configure.ac:329: error: possibly undefined macro: AC_MSG_FAILURE