ubik: Don't record result of select()

We never do anything with the return value from select(), so don't
bother storing it into code.

Caught by clang-analyzer

Change-Id: I6e0352b74f0e90b62ad32a3ef1a9d0173bf307ee
Reviewed-on: http://gerrit.openafs.org/9181
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>