pgsql: Add JIT counters to pg_stat_statements

Add JIT counters to pg_stat_statements

This adds cumulative counters for jit operations to pg_stat_statements,
making it easier to diagnose how JIT is used in an installation.

These changes merge into the 1.10 changes applied in 76cbf7edb6 without
creating a new version.

Reviewed-By: Julien Rouhaud
Discussion: /messages/by-id/CABUevEySt4NTYqvWzwyAW_0-jG1bjN-y+tykapAnA0FALOs+Lw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/57d6aea00fcefec3825a5948ce05cf2b4941097b

Modified Files
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.../pg_stat_statements/expected/oldextversions.out | 84 ++++++++++++----------
.../pg_stat_statements--1.9--1.10.sql | 10 ++-
contrib/pg_stat_statements/pg_stat_statements.c | 50 ++++++++++++-
doc/src/sgml/pgstatstatements.sgml | 72 +++++++++++++++++++
4 files changed, 175 insertions(+), 41 deletions(-)