Add missing return statement in ApexFile.verifyDescriptor

Fixed other places in apexd that didn't use resulting Status/StatusOr.
Didn't mark Status and StatusOr as WARN_UNUSED as it will require
changing code outside of apexd. Instead fixed them in AOSP.

Test: m apexd
Bug: 135682248
Fixes: 135682248
Change-Id: I3e362b3284bcdcc7e6d68e4691dc4f042f3af1da
Merged-In: I3e362b3284bcdcc7e6d68e4691dc4f042f3af1da