Also, make an internal _getprogname() that is used only inside
libc. For libc, getprogname(3) is a weak symbol in case a
function of the same name is defined in userland.
in my tree for a long time. bde reviewed this once upon a time and
said it was OK, iirc. This also obviates the need to put ? in the
optstring argument to preclude the extra warning message which some
people think confuses users. When I made my getopt cleanups of a long
time ago, this was the compromise reached. I just neglected to commit
it until now.
