Make more use of *_NAME macros.
* configure.ac (GPG_DISP_NAME, GPGSM_DISP_NAME): New. (GPG_AGENT_DISP_NAME, SCDAEMON_DISP_NAME): New. (DIRMNGR_DISP_NAME, G13_DISP_NAME): New. (GPGCONF_DISP_NAME): New. (SCDAEMON_SOCK_NAME): New. * common/argparse.c (show_help): Map description string.