Update copyrights that were missed.

contrib/dblink/dblink.c

contrib/dblink/dblink.h

contrib/dbsize/dbsize.c

contrib/findoidjoins/findoidjoins.c

contrib/fuzzystrmatch/fuzzystrmatch.c

contrib/fuzzystrmatch/fuzzystrmatch.h

contrib/tablefunc/tablefunc.c

contrib/tablefunc/tablefunc.h

src/backend/access/heap/tuptoaster.c

src/backend/access/transam/varsup.c

src/backend/commands/prepare.c

src/backend/executor/instrument.c

src/backend/postmaster/pgstat.c

src/backend/utils/adt/ascii.c

src/backend/utils/adt/encode.c

src/backend/utils/adt/formatting.c

src/backend/utils/adt/lockfuncs.c

src/backend/utils/adt/numeric.c

src/backend/utils/adt/pg_locale.c

src/backend/utils/adt/quote.c