Mark functions as static and ifdef NOT_USED as appropriate.

src/backend/access/index/istrat.c

src/backend/access/nbtree/nbtinsert.c

src/backend/access/transam/xact.c

src/backend/catalog/index.c

src/backend/commands/async.c

src/backend/commands/comment.c

src/backend/commands/trigger.c

src/backend/executor/nodeTidscan.c

src/backend/lib/dllist.c

src/backend/nodes/nodeFuncs.c

src/backend/optimizer/path/clausesel.c

src/backend/optimizer/plan/createplan.c

src/backend/optimizer/prep/prepqual.c

src/backend/optimizer/util/joininfo.c

src/backend/optimizer/util/tlist.c

src/backend/parser/parse_clause.c

src/backend/parser/parse_relation.c

src/backend/parser/parse_type.c

src/backend/storage/buffer/bufmgr.c

src/backend/storage/file/buffile.c