pgsql: Handle numeric overflow when handling range values

Handle numeric overflow when handling range values

The numrange_subdiff() function was calculating the difference simply by
calling numeric_sub and numeric_float8, but those functions are not
overflow-safe. It's possible to insert valid numeric ranges for which
the difference overflows either numeric or float8.

The overflow may affect various operations on numrange columns. It may
cause failures during ANALYZE on the table, inserts into GiST indexes,
selectivity estimation, and possibly other operations.

Fixed by handling overflows in numrange_subdiff() - extreme differences
are treated as infinity.

Author: Kirill Reshke <reshkekirill(at)gmail(dot)com>
Reviewed-by: shihao zhong <zhong950419(at)gmail(dot)com>
Backpatch-through: 14
Discussion: https://postgr.es/m/CALdSSPgBvXz-VSF0p-5k%3D_uFfN38cWrERmm_AC4K67N6MWQhmg%40mail.gmail.com

Branch
------
REL_15_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/10686da4eddb5f37ecb1a3467c1c411cd1c84003

Modified Files
--------------
src/backend/utils/adt/rangetypes.c | 37 ++++++++++++++++++++++-----
src/test/regress/expected/multirangetypes.out | 7 +++++
src/test/regress/sql/multirangetypes.sql | 9 +++++++
3 files changed, 46 insertions(+), 7 deletions(-)