[AArch64_be] Fix vec_select hi/lo mask confusions.

[AArch64_be] Fix vec_select hi/lo mask confusions.

gcc/

	* config/aarch64/aarch64.c (aarch64_simd_vect_par_cnst_half): Vary
	the generated mask based on BYTES_BIG_ENDIAN.
	(aarch64_simd_check_vect_par_cnst_half): New.
	* config/aarch64/aarch64-protos.h
	(aarch64_simd_check_vect_par_cnst_half): New.
	* config/aarch64/predicates.md (vect_par_cnst_hi_half): Refactor
	the check out to aarch64_simd_check_vect_par_cnst_half.
	(vect_par_cnst_lo_half): Likewise.
	* config/aarch64/aarch64-simd.md
	(aarch64_simd_move_hi_quad_<mode>): Always use vec_par_cnst_lo_half.
	(move_hi_quad_<mode>): Always generate a low mask.

From-SVN: r213378