CertVerifyProcAndroid: return error if the verified cert chain is empty

It's theoretically possible the java certificate verification code
can return a success status while also returning an empty
verified_chain, and there are some crash reports of a CHECK_EQ in
CertVerifyProc::Verify that indicate this may actually be happening.
(At least I don't see any other code path that could lead to that
check getting hit.)

If the verified_chain is empty, add a cert_status error to ensure
that this gets interpreted as a failure even if the status that was
returned from the java code wasn't a failure.

Also initialize status before calling android::VerifyX509CertChain.
(From code examination it appears that it will always be set, but
this makes it more obviously correct.)

Bug: 437733078
Change-Id: I5600e71c32b4f6914d1b8ae81c29e04d18365ddb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6847078
Reviewed-by: Nick Harper <nharper@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1501054}