re PR tree-optimization/64006 (__builtin_mul_overflow fails to signal overflow)

re PR tree-optimization/64006 (__builtin_mul_overflow fails to signal overflow)

	PR tree-optimization/64006
	* tree-vrp.c (stmt_interesting_for_vrp): Return true
	for {ADD,SUB,MUL}_OVERFLOW internal calls.
	(vrp_visit_assignment_or_call): For {ADD,SUB,MUL}_OVERFLOW
	internal calls, check if any REALPART_EXPR/IMAGPART_EXPR
	immediate uses would change their value ranges and return
	SSA_PROP_INTERESTING if so, or SSA_PROP_NOT_INTERESTING
	if there are some REALPART_EXPR/IMAGPART_EXPR immediate uses
	interesting for vrp.

	* gcc.c-torture/execute/pr64006.c: New test.

From-SVN: r217945