Re-enabled variables in fetch/move command.

src/interfaces/ecpg/ChangeLog

src/interfaces/ecpg/ecpglib/descriptor.c

src/interfaces/ecpg/ecpglib/execute.c

src/interfaces/ecpg/ecpglib/extern.h

src/interfaces/ecpg/preproc/pgc.l

src/interfaces/ecpg/preproc/preproc.y

src/interfaces/ecpg/test/expected/sql-fetch.c

src/interfaces/ecpg/test/sql/fetch.pgc