Add SET statement_timeout capability. Timeout is in ms. A value of

doc/src/sgml/runtime.sgml

src/backend/postmaster/postmaster.c

src/backend/storage/lmgr/proc.c

src/backend/tcop/postgres.c

src/backend/utils/misc/guc.c

src/backend/utils/misc/postgresql.conf.sample

src/bin/psql/tab-complete.c

src/include/storage/proc.h