fold-const.c (fold_comparison): Clean up and extend X +- C1 CMP C2 to X CMP C2 -+ C1 transformation to...

	* fold-const.c (fold_comparison): Clean up and extend X +- C1 CMP C2
	to X CMP C2 -+ C1 transformation to EQ_EXPR/NE_EXPR.
	Add X - Y CMP 0 to X CMP Y transformation.
	(fold_binary_loc) <EQ_EXPR/NE_EXPR>: Remove same transformations.

From-SVN: r210979