pgsql: Fix two comments in numeric.c

Fix two comments in numeric.c

The comments at the top of numeric_int4_safe() and numeric_int8_safe()
mentioned respectively int4_numeric() and int8_numeric().  The intention
is to refer to numeric_int4() and numeric_int8().

Oversights in 4246a977bad6.

Reported-by: jian he <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxFfVt7Jx9_j=juxXyP-6tznN8OcvS9E-QSgp0BrD8KUgA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/0c7f103028202cec94e12cbe45cebdb5c8fbc392

Modified Files
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src/backend/utils/adt/numeric.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)