pgsql: Support configurable eventlog application names on Windows

Support configurable eventlog application names on Windows

This allows different instances to use the eventlog with different
identifiers, by setting the event_source GUC, similar to how
syslog_ident works.

Original patch by MauMau, heavily modified by Magnus Hagander

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/d8ea33f2c02721c89c2434b9fda170afb7fe4999

Modified Files
--------------
doc/src/sgml/config.sgml                      |   25 +++++++++++
doc/src/sgml/installation.sgml                |   13 ------
doc/src/sgml/runtime.sgml                     |   46 +++++++++++++++++++
src/backend/utils/error/elog.c                |    3 +-
src/backend/utils/misc/guc.c                  |   14 ++++++
src/backend/utils/misc/postgresql.conf.sample |    2 +
src/bin/pgevent/pgevent.c                     |   58 ++++++++++++++++++++++--
src/bin/pgevent/pgevent.def                   |    1 +
8 files changed, 143 insertions(+), 19 deletions(-)