CameraMetadataNative: Fix FD leak in dump.

Always close the read end of the socketpair. In addition, return
early if pthread_create fails. If we don't do this, we risk blocking
forever on the read() and/or calling pthread_join on an undefined
pthread_t.

Test: run cts -m CtsCameraTestCases;

Change-Id: I9adb872ac2dbca2474e04707b77945b0a08d9432