backport: re PR rtl-optimization/87065 (combine causes ICE in trunc_int_for_mode)

backport: re PR rtl-optimization/87065 (combine causes ICE in trunc_int_for_mode)

	Backported from mainline
	2018-08-27  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/87065
	* combine.c (simplify_if_then_else): Formatting fix.
	(if_then_else_cond): Guard MULT optimization with SCALAR_INT_MODE_P
	check.
	(known_cond): Don't return const_true_rtx for vector modes.  Use
	CONST0_RTX instead of const0_rtx.  Formatting fixes.

	* gcc.target/i386/pr87065.c: New test.

From-SVN: r265110