configury: improve dlsym underscore detection.

* configure.ac (fn_module_cmds): Split ~ delimited command lists,
and set globals required by $module_cmds and $archive_cmds.
(libname): Preload with 'conftmod' ready for fun_module_cmds
calls, and for reuse as an 8.3 compatible module basename in this
check.
(sys_dlsym_uscore): Use it to detect underscore prefix requirement
in some dlysm() implementations more reliably.
Reported by KO Myung-Hun

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
1 file changed