This patch adds absolute jump table support for rs6000.

This patch adds absolute jump table support for rs6000.

gcc/ChangeLog:

	* config/rs6000/rs6000-protos.h (rs6000_output_addr_vec_elt): Declare.
	* config/rs6000/rs6000.c (TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC):
	Define.
	(rs6000_gen_pic_addr_diff_vec, rs6000_output_addr_vec_elt): Implement.
	* config/rs6000/rs6000.h (CASE_VECTOR_PC_RELATIVE,
	CASE_VECTOR_MODE, ASM_OUTPUT_ADDR_VEC_ELT): Define.
	* config/rs6000/rs6000.md (tablejump<mode>_absolute,
	tablejump<mode>_absolute_nospec): New expanders.
	* config/rs6000/rs6000.opt (mrelative-jumptables): New.