c/111468 - dump unordered compare operators in their GIMPLE form with -gimple

The following adjusts -gimple dumping to dump the unordered compare ops
and *h in their GIMPLE form.  It also adds parsing for __LTGT which I
missed before.

	PR c/111468
gcc/c/
	* gimple-parser.cc (c_parser_gimple_binary_expression): Handle __LTGT.

gcc/
	* tree-pretty-print.h (op_symbol_code): Add defaulted flags
	argument.
	* tree-pretty-print.cc (op_symbol): Likewise.
	(op_symbol_code): Print TDF_GIMPLE variant if requested.
	* gimple-pretty-print.cc (dump_binary_rhs): Pass flags to
	op_symbol_code.
	(dump_gimple_cond): Likewise.

gcc/testsuite/
	* gcc.dg/gimplefe-50.c: Amend.