pgsql: Convert lwlock.c to use the new shmem allocation functions

Convert lwlock.c to use the new shmem allocation functions

It seems like a good candidate to convert first because it needs to
initialized before any other subsystem, but other than that it's
nothing special.

Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://www.postgresql.org/message-id/CAExHW5vM1bneLYfg0wGeAa=52UiJ3z4vKd3AJ72X8Fw6k3KKrg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a006bc7b1699d952afcb6d786343e8bf0ecc61d6

Modified Files
--------------
src/backend/postmaster/postmaster.c |  16 +++---
src/backend/storage/ipc/ipci.c      |  13 -----
src/backend/storage/lmgr/lwlock.c   | 100 +++++++++++++++++-------------------
src/backend/tcop/postgres.c         |  16 +++---
src/include/storage/lwlock.h        |   2 -
src/include/storage/subsystemlist.h |   9 +++-
6 files changed, 75 insertions(+), 81 deletions(-)