pgsql: Clean up most -Wunused-but-set-variable warnings from gcc 4.6

Clean up most -Wunused-but-set-variable warnings from gcc 4.6

This warning is new in gcc 4.6 and part of -Wall. This patch cleans
up most of the noise, but there are some still warnings that are
trickier to remove.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/5caa3479c2efd31fca1b271db687e5e57c7de2d4

Modified Files
--------------
contrib/isn/isn.c | 10 ++----
contrib/pageinspect/fsmfuncs.c | 2 -
contrib/pgcrypto/pgp-s2k.c | 12 ++------
contrib/pgcrypto/px-hmac.c | 2 -
contrib/pgcrypto/px.c | 6 +---
contrib/seg/seg.c | 3 +-
src/backend/access/gist/gistvacuum.c | 5 ---
src/backend/access/nbtree/nbtpage.c | 3 +-
src/backend/catalog/pg_proc.c | 4 --
src/backend/catalog/toasting.c | 3 +-
src/backend/commands/explain.c | 2 -
src/backend/commands/tablecmds.c | 2 -
src/backend/commands/tsearchcmds.c | 4 +--
src/backend/commands/vacuum.c | 6 +---
src/backend/executor/nodeHashjoin.c | 2 -
src/backend/executor/nodeMergejoin.c | 2 -
src/backend/executor/nodeRecursiveunion.c | 7 +---
src/backend/foreign/foreign.c | 3 --
src/backend/libpq/auth.c | 7 ++--
src/backend/optimizer/geqo/geqo_main.c | 11 ++++--
src/backend/parser/parse_utilcmd.c | 3 +-
src/backend/rewrite/rewriteDefine.c | 3 +-
src/backend/storage/ipc/standby.c | 4 --
src/backend/storage/smgr/md.c | 3 +-
src/backend/utils/adt/ri_triggers.c | 3 --
src/backend/utils/adt/selfuncs.c | 6 ----
src/bin/pg_dump/common.c | 45 +++++++++-------------------
src/bin/pg_dump/pg_backup_custom.c | 3 +-
src/bin/pg_dump/pg_dump.c | 37 ++----------------------
src/bin/pg_dump/pg_dumpall.c | 12 ++------
src/bin/psql/psqlscan.l | 7 +---
src/interfaces/ecpg/ecpglib/descriptor.c | 23 ++++++--------
src/interfaces/libpq/fe-auth.c | 5 +--
src/pl/plpgsql/src/pl_exec.c | 2 -
34 files changed, 64 insertions(+), 188 deletions(-)