Add undefined behavior sanitizer in `build_oai`, fix some errors
- Adds UBSan to option
--sanitize-address
and--sanitize
(implying--sanitize-address
and--sanitize-undefined
) tobuild_oai
- Fixes a couple of bugs found with it.
--sanitize-address
and --sanitize
(implying --sanitize-address
and --sanitize-undefined
) to build_oai