Don't settle for any dumpbin/link program as name lister.

Don't settle for any dumpbin/link program as name lister.

* libltdl/m4/libtool.m4 (LT_PATH_NM): When locating dumpbin or
link -dump, check if they appear to really be capable of name
listing, in order to eliminate e.g. link from coreutils. This
makes the name lister decision fall back on nm as the default if
no acceptable candidate is found, which mainly happens on
(arguably broken) cross compiles.
* NEWS: Update
* THANKS: Update
Reports by Rudolf Leitgeb and Peter Kjellerstedt.

Signed-off-by: Peter Rosin <peda@lysator.liu.se>
Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>