re PR rtl-optimization/47525 (DCE fails to eliminate a dead call to a pure function when compiled with -maltivec)

	PR rtl-optimization/47525
	* df-scan.c: Update copyright years.
	(df_get_call_refs): Do not mark global registers as DF_REF_REG_USE
	and non-clobber DF_REF_REG_DEF for calls to const and pure functions.

From-SVN: r169768