re PR rtl-optimization/56571 (ICE in copyprop_hardreg_forward_1, at regcprop.c (insn does not satisfy its constraints !))

	PR middle-end/56571
	* valtrack.c (cleanup_auto_inc_dec): Unshare clobbers originating
	from pseudos.
	* emit-rtl.c (verify_rtx_sharing): Likewise.
	(copy_insn_1): Likewise.
	* rtl.c (copy_rtx): Likewise.
	PR middle-end/56571
	* gcc.c-torture/compile/pr56571.c: New testcase.

From-SVN: r196612