rtx_writer: avoid printing trailing default values

rtx_writer: avoid printing trailing default values

gcc/ChangeLog:
	* print-rtl.c (rtx_writer::operand_has_default_value_p): New
	method.
	(rtx_writer::print_rtx): In compact mode, omit trailing operands
	that have the default values.
	* print-rtl.h (rtx_writer::operand_has_default_value_p): New
	method.
	* rtl-tests.c (selftest::test_dumping_insns): Remove empty
	label string from expected dump.
	(seltest::test_uncond_jump): Remove trailing "(nil)" for REG_NOTES
	from expected dump.

From-SVN: r241908