Removed some variables no longer needed.

src/interfaces/ecpg/ChangeLog

src/interfaces/ecpg/compatlib/informix.c

src/interfaces/ecpg/pgtypeslib/interval.c

src/interfaces/ecpg/pgtypeslib/numeric.c

src/interfaces/ecpg/pgtypeslib/timestamp.c

src/interfaces/ecpg/preproc/type.c