Remove QNX port.

configure

configure.in

doc/FAQ_QNX4

doc/src/sgml/installation.sgml

doc/src/sgml/runtime.sgml

src/backend/Makefile

src/backend/bootstrap/Makefile

src/backend/port/Makefile

src/backend/port/dynloader/qnx4.c

src/backend/port/dynloader/qnx4.h

src/backend/port/qnx4/Makefile

src/backend/port/qnx4/ipc.h

src/backend/port/qnx4/isnan.c

src/backend/port/qnx4/sem.c

src/backend/port/qnx4/sem.h

src/backend/port/qnx4/shm.c

src/backend/port/qnx4/shm.h

src/backend/port/qnx4/tstsem.c

src/backend/port/qnx4/tstshm.c

src/backend/utils/misc/ps_status.c