Bogus and missed folding on vector compares

Bogus and missed folding on vector compares

fold_binary tries to transform (double)float1 CMP (double)float2
into float1 CMP float2 but ends up using TYPE_PRECISION on the
argument types.  For vector types that compares the number of
lanes which should be always equal (so it's harmless as to
not generating wrong code).  The following instead properly
uses element_precision.

The same happens in the corresponding match.pd pattern.

	* fold-const.cc (fold_binary_loc): Use element_precision
	when trying (double)float1 CMP (double)float2 to
	float1 CMP float2 simplification.
	* match.pd: Likewise.