pgsql: In pg_upgrade, add -o/-O options to pass parameters to the serve

In pg_upgrade, add -o/-O options to pass parameters to the servers, and
document its use for config-only directory installs.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/0dc3f57ba0aa9a99308d3d097eeb2cbcbd5fb52c

Modified Files
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contrib/pg_upgrade/option.c     |   19 ++++++++++++++++++-
contrib/pg_upgrade/pg_upgrade.h |    1 +
contrib/pg_upgrade/server.c     |   28 +++++++++++-----------------
doc/src/sgml/pgupgrade.sgml     |   22 ++++++++++++++++++++++
4 files changed, 52 insertions(+), 18 deletions(-)