Support VERBOSE option in REINDEX command.

When this option is specified, a progress report is printed as each index
is reindexed.

Per discussion, we agreed on the following syntax for the extensibility of
the options.

    REINDEX (flexible options) { INDEX | ... } name

Sawada Masahiko.
Reviewed by Robert Haas, Fabrízio Mello, Alvaro Herrera, Kyotaro Horiguchi,
Jim Nasby and me.

Discussion: CAD21AoA0pK3YcOZAFzMae+2fcc3oGp5zoRggDyMNg5zoaWDhdQ@mail.gmail.com

src/test/regress/sql/create_index.sql

@@ -965,6 +965,14 @@ RESET enable_indexscan;
 explain (costs off)
   select * from tenk1 where (thousand, tenthous) in ((1,1001), (null,null));
 
+--
+-- REINDEX (VERBOSE)
+--
+CREATE TABLE reindex_verbose(id integer primary key);
+\set VERBOSITY terse
+REINDEX (VERBOSE) TABLE reindex_verbose;
+DROP TABLE reindex_verbose;
+
 --
 -- REINDEX SCHEMA
 --