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: https://www.postgresql.org/message-id/flat/CABUevEySt4NTYqvWzwyAW_0-jG1bjN-y+tykapAnA0FALOs+Lw@mail.gmail.com