pgsql: Improve reporting of run-time-detected indeterminate-collation e

Improve reporting of run-time-detected indeterminate-collation errors.

pg_newlocale_from_collation does not have enough context to give an error
message that's even a little bit useful, so move the responsibility for
complaining up to its callers.  Also, reword ERRCODE_INDETERMINATE_COLLATION
error messages in a less jargony, more message-style-guide-compliant
fashion.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/6e197cb2e537880f36828a6c55d0f6df5bf7daa8

Modified Files
--------------
src/backend/commands/collationcmds.c             |    2 +-
src/backend/commands/indexcmds.c                 |    2 +-
src/backend/commands/view.c                      |    2 +-
src/backend/utils/adt/formatting.c               |   78 ++++++++++++++++++++++
src/backend/utils/adt/pg_locale.c                |   14 +---
src/backend/utils/adt/varlena.c                  |   13 ++++
src/test/regress/expected/collate.linux.utf8.out |    6 +-
src/test/regress/expected/collate.out            |    6 +-
8 files changed, 105 insertions(+), 18 deletions(-)