fold-const.c (fold_unary): Ensure folded expressions are type correct.

	* fold-const.c (fold_unary) <CONJ_EXPR>: Ensure folded expressions
	are type correct.  Clean-up.
	<REALPART_EXPR>: Likewise.  Optimize creal(~z) as creal(z).
	<IMAGPART_EXPR>: Likewise.  Optimize cimag(~z) as -cimag(z).

From-SVN: r114330