LU-14588 o2ib: make config script aware of the ofed symbols

LU-14588 o2ib: make config script aware of the ofed symbols

LNet o2ib configuration script needs to be aware of the external
ofed dkms symbols when testing for availability of o2ib features
by building "conftest" kernel objects. If this is not done,
symbols from the core kernel are used by default which is
different from what is used when actually building LNet,
at least on Ubuntu. This patch adds the check for external symbols.

Lustre-commit: bcc5d784826d2d7a8eece28e96fab8b0fa02ab17
Lustre-change: https://review.whamcloud.com/43223

Test-Parameters: trivial
Signed-off-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Change-Id: Iea566f8a3feb86b8bef2f4501a3abc968d76451a
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/43459
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>