pgsql: Improve scripting language in pgbench

Improve scripting language in pgbench

Added:
 - variable now might contain integer, double, boolean and null values
 - functions ln, exp
 - logical AND/OR/NOT
 - bitwise AND/OR/NOT/XOR
 - bit right/left shift
 - comparison operators
 - IS [NOT] (NULL|TRUE|FALSE)
 - conditional choice (in form of when/case/then)

New operations and functions allow to implement more complicated test scenario.

Author: Fabien Coelho with minor editorization by me
Reviewed-By: Pavel Stehule, Jeevan Ladhe, me
Discussion: https://www.postgresql.org/message-id/flat/alpine.DEB.2.10.1604030742390.31618@sto

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/bc7fa0c15c590ddf4872e426abd76c2634f22aca

Modified Files
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doc/src/sgml/ref/pgbench.sgml                | 223 +++++++++++-
src/bin/pgbench/exprparse.y                  | 195 ++++++++++-
src/bin/pgbench/exprscan.l                   |  55 ++-
src/bin/pgbench/pgbench.c                    | 484 +++++++++++++++++++++++----
src/bin/pgbench/pgbench.h                    |  24 +-
src/bin/pgbench/t/001_pgbench_with_server.pl | 171 ++++++++--
6 files changed, 1026 insertions(+), 126 deletions(-)