pgsql: Add DECLARE STATEMENT command to ECPG

Add DECLARE STATEMENT command to ECPG

This command declares a SQL identifier for a SQL statement to be used in other
embedded SQL statements. The identifier is linked to a connection.

Author: Hayato Kuroda <kuroda(dot)hayato(at)fujitsu(dot)com>
Reviewed-by: Shawn Wang <shawn(dot)wang(dot)pg(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/TY2PR01MB24438A52DB04E71D0E501452F5630(at)TY2PR01MB2443(dot)jpnprd01(dot)prod(dot)outlook(dot)com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/ad8305a43d1890768a613d3fb586b44f17360f29

Modified Files
--------------
doc/src/sgml/ecpg.sgml | 140 ++++-
src/interfaces/ecpg/preproc/ecpg.addons | 90 +++-
src/interfaces/ecpg/preproc/ecpg.c | 9 +
src/interfaces/ecpg/preproc/ecpg.header | 25 +
src/interfaces/ecpg/preproc/ecpg.trailer | 45 +-
src/interfaces/ecpg/preproc/ecpg.type | 1 +
src/interfaces/ecpg/preproc/preproc_extern.h | 1 +
src/interfaces/ecpg/preproc/type.h | 7 +
src/interfaces/ecpg/test/ecpg_schedule | 1 +
src/interfaces/ecpg/test/expected/sql-declare.c | 580 +++++++++++++++++++++
.../ecpg/test/expected/sql-declare.stderr | 286 ++++++++++
.../ecpg/test/expected/sql-declare.stdout | 20 +
src/interfaces/ecpg/test/sql/.gitignore | 2 +
src/interfaces/ecpg/test/sql/Makefile | 1 +
src/interfaces/ecpg/test/sql/declare.pgc | 207 ++++++++
15 files changed, 1398 insertions(+), 17 deletions(-)