pgsql: Arrange to emit a description of the current XLOG record as error

Log Message:
-----------
Arrange to emit a description of the current XLOG record as error context
when an error occurs during xlog replay. Also, replace the former risky
'write into a fixed-size buffer with no overflow detection' API for XLOG
record description routines; use an expansible StringInfo instead. (The
latter accounts for most of the patch bulk.)

Qingqing Zhou

Modified Files:
--------------
pgsql/src/backend/access/gist:
gistxlog.c (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistxlog.c.diff?r1=1.10&r2=1.11)
pgsql/src/backend/access/hash:
hash.c (r1.87 -> r1.88)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/hash/hash.c.diff?r1=1.87&r2=1.88)
pgsql/src/backend/access/heap:
heapam.c (r1.208 -> r1.209)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/heap/heapam.c.diff?r1=1.208&r2=1.209)
pgsql/src/backend/access/nbtree:
nbtxlog.c (r1.26 -> r1.27)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/nbtree/nbtxlog.c.diff?r1=1.26&r2=1.27)
pgsql/src/backend/access/transam:
clog.c (r1.37 -> r1.38)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/clog.c.diff?r1=1.37&r2=1.38)
multixact.c (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/multixact.c.diff?r1=1.16&r2=1.17)
xact.c (r1.217 -> r1.218)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c.diff?r1=1.217&r2=1.218)
xlog.c (r1.227 -> r1.228)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c.diff?r1=1.227&r2=1.228)
pgsql/src/backend/commands:
dbcommands.c (r1.177 -> r1.178)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/dbcommands.c.diff?r1=1.177&r2=1.178)
sequence.c (r1.129 -> r1.130)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/sequence.c.diff?r1=1.129&r2=1.130)
tablespace.c (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablespace.c.diff?r1=1.31&r2=1.32)
pgsql/src/backend/storage/smgr:
smgr.c (r1.96 -> r1.97)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/smgr/smgr.c.diff?r1=1.96&r2=1.97)
pgsql/src/include/access:
clog.h (r1.16 -> r1.17)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/clog.h.diff?r1=1.16&r2=1.17)
gist_private.h (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/gist_private.h.diff?r1=1.10&r2=1.11)
hash.h (r1.66 -> r1.67)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/hash.h.diff?r1=1.66&r2=1.67)
heapam.h (r1.106 -> r1.107)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/heapam.h.diff?r1=1.106&r2=1.107)
multixact.h (r1.9 -> r1.10)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/multixact.h.diff?r1=1.9&r2=1.10)
nbtree.h (r1.92 -> r1.93)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/nbtree.h.diff?r1=1.92&r2=1.93)
xact.h (r1.80 -> r1.81)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xact.h.diff?r1=1.80&r2=1.81)
xlog.h (r1.70 -> r1.71)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xlog.h.diff?r1=1.70&r2=1.71)
xlog_internal.h (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/xlog_internal.h.diff?r1=1.10&r2=1.11)
pgsql/src/include/commands:
dbcommands.h (r1.44 -> r1.45)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/dbcommands.h.diff?r1=1.44&r2=1.45)
sequence.h (r1.35 -> r1.36)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/sequence.h.diff?r1=1.35&r2=1.36)
tablespace.h (r1.12 -> r1.13)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/tablespace.h.diff?r1=1.12&r2=1.13)
pgsql/src/include/storage:
smgr.h (r1.54 -> r1.55)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/smgr.h.diff?r1=1.54&r2=1.55)