re PR rtl-optimization/11210 (optimizer drops conditional with typecast from signed...

re PR rtl-optimization/11210 (optimizer drops conditional with typecast from signed to unsigned char)

	PR optimization/11210
	* expr.c (handled_component_p) [NOP_EXPR]: Add ??? note
	about the behaviour with regard to bitfields.
	* fold-const (decode_field_reference): Record outermost type in
	case the expression is a NOP. Strip all NOPs. Set the signedness
	to that of the outermost type (if any) when the bitsize is equal
	to the size of the type.

From-SVN: r68823