pgsql: Have pg_itoa, pg_ltoa and pg_lltoa return the length of the stri

Have pg_itoa, pg_ltoa and pg_lltoa return the length of the string

Core by no means makes excessive use of these functions, but quite a large
number of those usages do require the caller to call strlen() on the
returned string.  This is quite wasteful since these functions do already
have a good idea of the length of the string, so we might as well just
have them return that.

Reviewed-by: Andrew Gierth
Discussion: https://postgr.es/m/CAApHDvrm2A5x2uHYxsqriO2cUaGcFvND%2BksC9e7Tjep0t2RK_A%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dad75eb4a8d5835ecc795d7a7978e7702e4d5912

Modified Files
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src/backend/access/common/printsimple.c | 10 ++++++----
src/backend/utils/adt/int.c             |  4 +---
src/backend/utils/adt/int8.c            | 11 +++++++++--
src/backend/utils/adt/numutils.c        | 32 +++++++++++++++++++-------------
src/include/utils/builtins.h            |  6 +++---
5 files changed, 38 insertions(+), 25 deletions(-)