Run tests of libpq on installcheck-world, checkprep and check-world

Run tap tests in src/interfaces/libpq.

Convert src/interfaces/libpq/test to a tap test.

Fix slow animal timeouts in 032_relfilenode_reuse.pl.

Add logging for excessive ProcSignalBarrier waits.

Fix race in 032_relfilenode_reuse.pl.

Fix old-fd issues using global barriers everywhere.

Rethink PROCSIGNAL_BARRIER_SMGRRELEASE.

Fix waiting in RegisterSyncRequest().

Wake up for latches in CheckpointWriteDelay().

perl tap: Show die reason in TAP output

pg_regress: Emit TAP compliant output