configure.in: Add check for GAS subsection -1 support.

configure.in: Add check for GAS subsection -1 support.

	* configure.in: Add check for GAS subsection -1 support.
	* acconfig.h (HAVE_GAS_SUBSECTION_ORDERING): Add.
	* configure config.in: Rebuilt.
	* config/sparc/sparc.h (CASE_VECTOR_MODE): For V9 flag_pic, use
	SImode is subsection -1 works, else use DImode.
	(ASM_OUTPUT_ADDR_VEC_START, ASM_OUTPUT_ADDR_VEC_END): Define if
	subsection -1 works.
	* config/sparc/sparc.c (sparc_output_addr_vec,
	sparc_output_addr_diff_vec): Use them if defined.

From-SVN: r22383