re PR tree-optimization/29921 (internal compiler error: in set_lattice_value, at tree-ssa-ccp.c:437)

	PR tree-optimization/29921
	* fold-const.c (operand_equal_p): Without HONOR_SIGNED_ZEROS, consider
	signed and unsigned zero equal.

	* gcc.dg/pr29921.c: New test.

From-SVN: r119102