Regression test for a crash (#66923) in outgoing calls
to a built-in function (unsafe.Slice).

-- go.mod --
module example.com
go 1.17

-- a/a.go --
package a

import "unsafe"

func A() []int { //@ loc(A, "A"), outgoingcalls(A, UNSAFE)
	return unsafe.Slice(new(int), 1)
}
