* configure.ac: Tidy target case.
        (HAVE_LONG_DOUBLE): Allow the target to override.
        * configure: Regenerate.
        * include/ffi.h.in: Don't define ffi_type_foo if
        LIBFFI_HIDE_BASIC_TYPES is defined.
        (ffi_type_longdouble): If not HAVE_LONG_DOUBLE, define
        to ffi_type_double.
        * types.c (LIBFFI_HIDE_BASIC_TYPES): Define.
        (FFI_TYPEDEF, ffi_type_void): Mark the data const.
        (ffi_type_longdouble): Special case for Alpha.  Don't define
        if long double == double.

        * src/alpha/ffi.c (FFI_TYPE_LONGDOUBLE): Assert unique value.
        (ffi_prep_cif_machdep): Handle it as the 128-bit type.
        (ffi_call, ffi_closure_osf_inner): Likewise.
        (ffi_closure_osf_inner): Likewise.  Mark hidden.
        (ffi_call_osf, ffi_closure_osf): Mark hidden.
        * src/alpha/ffitarget.h (FFI_LAST_ABI): Tidy definition.
        * src/alpha/osf.S (ffi_call_osf, ffi_closure_osf): Mark hidden.
        (load_table): Handle 128-bit long double.

        * testsuite/libffi.call/float4.c: Add -mieee for alpha.

From-SVN: r123622