Fix verification of switch offsets in large methods.

The verifier was only using the low 16 bits when checking the offset
to a switch table.  This was failing on really large methods.

We also blew up the arbitrary size cap again, so I made it a warning
rather than a failure (it really wasn't doing anybody any good).

Changed to width-specific types for the various offsets and sizes.

Bug 3044850.

(cherry-pick+squash from dalvik-dev)

Change-Id: Ic7ebb86728cb39151f617a3e69e1c1994e61b5d9