Made sure sqlca is reset for declare cursor in Informix mode as pointed out by

src/interfaces/ecpg/ChangeLog

src/interfaces/ecpg/compatlib/Makefile

src/interfaces/ecpg/compatlib/exports.txt

src/interfaces/ecpg/compatlib/informix.c

src/interfaces/ecpg/include/ecpg_informix.h

src/interfaces/ecpg/preproc/ecpg.addons

src/interfaces/ecpg/preproc/ecpg.trailer

src/interfaces/ecpg/test/compat_informix/test_informix.pgc

...rfaces/ecpg/test/expected/compat_informix-test_informix.c

...s/ecpg/test/expected/compat_informix-test_informix.stderr

...s/ecpg/test/expected/compat_informix-test_informix.stdout

src/interfaces/ecpg/test/expected/connect-test1.stderr