build/autoconf: fix check for GNU ld version

build/autoconf: fix check for GNU ld version

we need to look for the version once in the stdout and once in the stderr
output. Some version of ld output to stdout, some output to stderr. redirecting
stderr to stdout messes the output up in our case, that's why we have to do two
runs. See also bug #7825.

Signed-off-by: Bjoern Jacke <bj@sernet.de>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Björn Jacke <bj@sernet.de>
Autobuild-Date(master): Tue Feb 19 20:56:12 CET 2013 on sn-devel-104
(cherry picked from commit ff8ba0628f6f13a5be1df94e5ac2e83008b7c69c)