pgsql: Fix function name in comment

Fix function name in comment

The name of the function resulting from the macro expansion was
incorrectly stated.

Backpatch to 16 where it was introduced.

Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20231101.172308.1740861597185391383.horikyota.ntt@gmail.com
Backpatch-through: v16

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/1155daef60548914e637b039d7b96cd824d0b71f

Modified Files
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src/backend/utils/adt/pgstatfuncs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)