Detect integer overflow in array_set_slice().

Detect integer overflow in array_set_slice().

When provided an empty initial array, array_set_slice() fails to
check for overflow when computing the new array's dimensions.
While such overflows are ordinarily caught by ArrayGetNItems(),
commands with the following form are accepted:

	INSERT INTO t (i[-2147483648:2147483647]) VALUES ('{}');

To fix, perform the hazardous computations using overflow-detecting
arithmetic routines.  As with commit 18b585155a, the added test
cases generate errors that include a platform-dependent value, so
we again use psql's VERBOSITY parameter to suppress printing the
message text.

Reported-by: Alexander Lakhin
Author: Joseph Koshakow
Reviewed-by: Jian He
Discussion: https://postgr.es/m/31ad2cd1-db94-bdb3-f91a-65ffdb4bef95%40gmail.com
Backpatch-through: 12