This renames and improves the VariableSizeBitCast helper from
util/linux/auxiliary_vector.* and moves it to misc.
Change-Id: I4bf46f4cfc0e60c900ff9bde467a21ad43c684cd
Reviewed-on: https://chromium-review.googlesource.com/534174
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>