pgsql: Use ProcNumbers instead of direct Latch pointers to address othe

Use ProcNumbers instead of direct Latch pointers to address other procs

This is in preparation for replacing Latches with a new abstraction.
That's still work in progress, but this seems a little tidier anyway,
so let's get this refactoring out of the way already.

Discussion: https://www.postgresql.org/message-id/391abe21-413e-4d91-a650-b663af49500c%40iki.fi

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a9c546a5a3783810a1b665f246fc6d0a596d0606

Modified Files
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src/backend/access/transam/xlog.c | 10 ++++++--
src/backend/access/transam/xlogwait.c | 15 ++++++------
src/backend/postmaster/checkpointer.c | 16 +++++++++----
src/backend/postmaster/walwriter.c | 6 ++---
.../libpqwalreceiver/libpqwalreceiver.c | 1 +
src/backend/replication/walreceiver.c | 16 ++++++-------
src/backend/replication/walreceiverfuncs.c | 11 +++++----
src/backend/storage/lmgr/proc.c | 4 ++--
src/include/access/xlogwait.h | 9 +++-----
src/include/replication/walreceiver.h | 27 +++++++++++-----------
src/include/storage/proc.h | 12 ++++++----
11 files changed, 72 insertions(+), 55 deletions(-)