`BinaryOperator::swapOperands` comment is out of date in implementation

[scottmcm]

Looks like maybe it used to change opcodes at some point in the past, but no longer does?

llvm-project/llvm/lib/IR/Instructions.cpp

Lines 2703 to 2712 in 070e129

	// Exchange the two operands to this instruction. This instruction is safe to
	// use on any binary instruction and does not modify the semantics of the
	// instruction. If the instruction is order-dependent (SetLT f.e.), the opcode
	// is changed.
	bool BinaryOperator::swapOperands() {
	if (!isCommutative())
	return true; // Can't commute operands
	Op<0>().swap(Op<1>());
	return false;
	}