+ improve CF_GNU_SOURCE configure macro to optionally define
_DEFAULT_SOURCE work around a nuisance in recent glibc releases.
+ move the terminfo-specific parts of tput's "reset" function into
the shared reset_cmd.c, making the two forms of reset use the same
strings.
+ split-out the terminal initialization functions from tset as
progs/reset_cmd.c, as part of changes to merge the reset-feature
with tput.
