[RS6000] Use gen_hard_reg_clobber in rs6000.c

[RS6000] Use gen_hard_reg_clobber in rs6000.c

I noticed when looking at PR88311 that rs6000_call_sysv should be
using gen_hard_reg_clobber (as the sysv call insns did prior to
introducing rs6000_call_sysv).  This patch fixes that minor
regression, and other like places in rs6000.c.

	* config/rs6000/rs6000.c (generate_set_vrsave, rs6000_emit_savres_rtx),
	(rs6000_emit_prologue, rs6000_call_aix, rs6000_call_sysv),
	(rs6000_call_darwin_1): Use gen_hard_reg_clobber.

From-SVN: r267164