pgsql: Add C comment mentioning pg_stat_activity.procpid should have be

Add C comment mentioning pg_stat_activity.procpid should have been
called 'pid'.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/a4bebdd92624e018108c2610fc3f2c1584b6c687

Modified Files
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src/backend/utils/adt/pgstatfuncs.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)