gralloc4-vts: Correct the ownership of fence fd

Gralloc::lock takes the ownership of acquireFence and closes the fence
by itself. The patch changes the behavior of fence to transfer the
ownership by unique_fd::release.

Bug: 157534008
Test: VtsHalGraphicsMapperV4_0TargetTest
Change-Id: Ie4ee9cd9c3b148cab9187fa07a4e52cbf9ad798a
1 file changed