pgsql: Fix comment for MAX_SIMUL_LWLOCKS.

Fix comment for MAX_SIMUL_LWLOCKS.

This comment mentions that pg_buffercache locks all buffer
partitions simultaneously, but it hasn't done so since v10.

Oversight in commit 6e654546fb.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/aKTuAHVEuYCUmmIy%40nathan

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/3eec0e65331e4a38d0c8b3ac251ea3885452fd71

Modified Files
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src/backend/storage/lmgr/lwlock.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)