pgsql: Improve API of GenericXLogRegister().

Improve API of GenericXLogRegister().

Rename this function to GenericXLogRegisterBuffer() to make it clearer
what it does, and leave room for other sorts of "register" actions in
future.  Also, replace its "bool isNew" argument with an integer flags
argument, so as to allow adding more flags in future without an API
break.

Alexander Korotkov, adjusted slightly by me

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/5713f03973e26ad6df6df5ac8b9efa0123d68062

Modified Files
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contrib/bloom/blinsert.c                  | 10 +++++-----
contrib/bloom/blutils.c                   |  9 +++++----
contrib/bloom/blvacuum.c                  |  4 ++--
doc/src/sgml/generic-wal.sgml             | 32 +++++++++++++++++--------------
src/backend/access/transam/generic_xlog.c | 10 ++++++----
src/include/access/generic_xlog.h         |  7 +++++--
6 files changed, 41 insertions(+), 31 deletions(-)