pgsql: Move strtoint() to common

Move strtoint() to common

Several places used similar code to convert a string to an int, so take
the function that we already had and make it globally available.

Reviewed-by: Michael Paquier <michael@paquier.xyz>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/17bb62501787c56e0518e61db13a523d47afd724

Modified Files
--------------
src/backend/nodes/read.c                  | 12 +++++-------
src/backend/parser/scan.l                 |  9 ++++-----
src/backend/utils/adt/datetime.c          | 18 +-----------------
src/common/string.c                       | 15 +++++++++++++++
src/include/common/string.h               |  1 +
src/interfaces/ecpg/pgtypeslib/.gitignore |  1 +
src/interfaces/ecpg/pgtypeslib/Makefile   |  6 +++++-
src/interfaces/ecpg/pgtypeslib/interval.c | 16 ++--------------
src/interfaces/ecpg/preproc/pgc.l         | 10 +++++-----
9 files changed, 39 insertions(+), 49 deletions(-)