configure.in: Add s390x-*-linux-* target.

configure.in: Add s390x-*-linux-* target.

	* configure.in: Add s390x-*-linux-* target.
	* configure: Regenerate.
	* include/ffi.h.in: Define S390X for s390x targets.
	(FFI_CLOSURES): Define for s390/s390x.
	(FFI_TRAMPOLINE_SIZE): Likewise.
	(FFI_NATIVE_RAW_API): Likewise.
	* src/prep_cif.c (ffi_prep_cif): Do not compute stack space for s390.
	* src/types.c (FFI_TYPE_POINTER): Use 8-byte pointers on s390x.
	* src/s390/ffi.c: Major rework of existing code.  Add support for
	s390x targets.  Add closure support.
	* src/s390/sysv.S: Likewise.

From-SVN: r57646