Mark libsuspend vendor_available.

libsuspend belongs to vndk-cap. Mark it vendor_available to enable vndk
abi stability checks on it.

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

Test: mm -j64

Bug: 38244611

Merged-In: Id716171806d71fabd9a67aa6a60189f30a35d2e2
Change-Id: I2243c6d8710b6b2f80375849e82afba28a735507
(cherry picked from commit e37259ec)