Detect overflows in constant expressions.

Currently these throw ubsan errors which are great for interface users,
because they are alerted about interface overflows. However, these are
holding up our fuzzer. In order to keep the fuzzer working, manually
handling these.

Bug: 161215757
Test: added corpus
Change-Id: I186e186f83bcee595cdc3f7db036510b3aa3e1e0
2 files changed