re PR middle-end/64182 (wide-int rounding division is broken)

re PR middle-end/64182 (wide-int rounding division is broken)

gcc/
	PR middle-end/64182
	* wide-int.h (wi::div_round, wi::mod_round): Fix rounding of tied
	cases.
	* double-int.c (div_and_round_double): Fix handling of unsigned
	cases.  Use same rounding approach as wide-int.h.

gcc/testsuite/
2014-xx-xx  Richard Sandiford  <richard.sandiford@arm.com>
	    Joseph Myers  <joseph@codesourcery.com>

	PR middle-end/64182
	* gcc.dg/plugin/wide-int-test-1.c,
	gcc.dg/plugin/wide-int_plugin.c: New test.
	* gcc.dg/plugin/plugin.exp: Register it.
	* gnat.dg/round_div.adb: New test.

Co-Authored-By: Joseph Myers <joseph@codesourcery.com>
From-SVN: r218678