MB-8481 Pass -Werror=strict-aliasing to GCC

So that strict aliasing warnings cause compilation to fail.
This class of warnings is too serious and shouldn't ever be
ignored.

Change-Id: I6da8fb9f11834673f309b9f152035d7b11821ffb
Reviewed-on: http://review.couchbase.org/26995
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Fulu Li <fulu@couchbase.com>
Tested-by: Aaron Miller <apage43@ninjawhale.com>