MY_LIB_READLINE tries each readline-compatible library with a sequence
of additional libraries, starting with none. If the check with none
fails, all the others checks reuse the cached result, and also fail.
Broken in commit 1cbda2c7d "client: Rewrite readline configuration",
v4.4.0.
Avoid the unwanted chaching.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
AX_LIB_READLINE tries to cope with systems where readline lacks
history support, or lacks headers, or needs headers included in
unorthodox ways. It puts six HAVE_ macros into config.h, and its
usage example takes 24 lines of code just to include two headers.
Way too complicated for my taste. Replace with new MY_LIB_READLINE,
which succeeds only when you have a sane readline, and then defines
*one* macro: HAVE_LIBREADLINE.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
