pgsql: Use ICU by default at initdb time.

Use ICU by default at initdb time.

If the ICU locale is not specified, initialize the default collator
and retrieve the locale name from that.

Discussion: https://postgr.es/m/510d284759f6e943ce15096167760b2edcb2e700.camel@j-davis.com
Reviewed-by: Peter Eisentraut

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/27b62377b47f9e7bf58613608bc718c86ea91e91

Modified Files
--------------
contrib/citext/expected/citext_utf8.out | 9 +++-
contrib/citext/expected/citext_utf8_1.out | 9 +++-
contrib/citext/sql/citext_utf8.sql | 9 +++-
contrib/unaccent/expected/unaccent.out | 9 ++++
contrib/unaccent/expected/unaccent_1.out | 8 ++++
contrib/unaccent/sql/unaccent.sql | 11 +++++
doc/src/sgml/ref/initdb.sgml | 53 +++++++++++++--------
src/bin/initdb/Makefile | 4 +-
src/bin/initdb/initdb.c | 54 +++++++++++++++++++++-
src/bin/initdb/t/001_initdb.pl | 7 +--
src/bin/pg_dump/t/002_pg_dump.pl | 2 +-
src/bin/scripts/t/020_createdb.pl | 2 +-
src/interfaces/ecpg/test/Makefile | 3 --
src/interfaces/ecpg/test/connect/test5.pgc | 2 +-
src/interfaces/ecpg/test/expected/connect-test5.c | 2 +-
.../ecpg/test/expected/connect-test5.stderr | 2 +-
src/interfaces/ecpg/test/meson.build | 1 -
src/test/icu/t/010_database.pl | 2 +-
18 files changed, 147 insertions(+), 42 deletions(-)