[NDS32] Implement DATA_ALIGNMENT, LOCAL_ALIGNMENT and TARGET_CONSTANT_ALIGNMENT.

gcc/
	* config/nds32/nds32-protos.h (nds32_data_alignment,
	nds32_local_alignment): Declare.
	* config/nds32/nds32.c (nds32_data_alignment, nds32_constant_alignment,
	nds32_local_alignment): New functions.
	(TARGET_CONSTANT_ALIGNMENT): Define.
	* config/nds32/nds32.h (DATA_ALIGNMENT, LOCAL_ALIGNMENT): Define.

From-SVN: r259548