Mark e2fs libs vendor_available.

libext2_blkid, libext2_com_err, libext2_e2p, libext2_uuid are libraries which
belong to vndk-cap. Mark them vendor_available to enable vndk abi stability
checks on them.

Details: https://android-review.googlesource.com/368372

Test: mm -j64

Bug: 38244611

Change-Id: I1931063b88b845a9a9d06188555c34f1fbc3e369
4 files changed