configure: add macro to check for __PROGNAME
Hi,
In include/c.h we check for different ways to get the program name:
#ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
# ifdef HAVE___PROGNAME
extern char *__progname;
# define program_invocation_short_name __progname
# else
# ifdef HAVE_GETEXECNAME
# define program_invocation_short_name \
prog_inv_sh_nm_from_file(getexecname(), 0)
# else
# define program_invocation_short_name \
prog_inv_sh_nm_from_file(__FILE__, 1)
# endif
static char prog_inv_sh_nm_buf[256];
However, the macro for setting HAVE__PROGNAME
seem to be missing from configure.ac, only way to use __progname is to modify the code or define HAVE__PROGNAME with some compiler flag.
This PR adds the missing macro, taken from tmux.
Related issue: #209 (closed)