* simplify-rtx.c (simplify_relational_operation_1):  Simplify
	(X^Y) == 0 as X == Y and (X^Y) != 0 as X != Y.  Simplify (X^Y) == Y
	as X == 0, and some symmetry related transformations.
	Simplify (X^C1) == C2 as X == (C1^C2).  Split long comment line.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@111443 138bc75d-0d04-0410-961f-82ee72b054a4