Support -rdynamic option in the new driver

This option does not have any effect for bitcode linking, but it is
supported by the existing driver and used by existing software packages
hence its use should not trigger an error.

BUG=https://bugs.chromium.org/p/nativeclient/issues/detail?id=4347
R=dschuff@chromium.org

Review URL: https://codereview.chromium.org/1834813002 .
1 file changed