pgsql: Don't set reachedMinRecoveryPoint during crash recovery. In cras

Don't set reachedMinRecoveryPoint during crash recovery. In crash recovery,
we don't reach consistency before replaying all of the WAL. Rename the
variable to reachedConsistency, to make its intention clearer.

In master, that was an active bug because of the recent patch to
immediately PANIC if a reference to a missing page is found in WAL after
reaching consistency, as Tom Lane's test case demonstrated. In 9.1 and 9.0,
the only consequence was a misleading "consistent recovery state reached at
%X/%X" message in the log at the beginning of crash recovery (the database
is not consistent at that point yet). In 8.4, the log message was not
printed in crash recovery, even though there was a similar
reachedMinRecoveryPoint local variable that was also set early. So,
backpatch to 9.1 and 9.0.

Branch
------
REL9_0_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/94b18c60c7a52452356bb49a04c1495083ea67f6

Modified Files
--------------
src/backend/access/transam/xlog.c |   21 +++++++++++++++++----
1 files changed, 17 insertions(+), 4 deletions(-)