Fix calling make with slice whose element type is size zero.

From-SVN: r179019

libgo/runtime/go-make-slice.c

@@ -35,7 +35,8 @@ __go_make_slice2 (const struct __go_type_descriptor *td, uintptr_t len,
   icap = (int) cap;
   if (cap < len
       || (uintptr_t) icap != cap
-      || cap > (uintptr_t) -1U / std->__element_type->__size)
+      || (std->__element_type->__size > 0
+	  && cap > (uintptr_t) -1U / std->__element_type->__size))
     __go_panic_msg ("makeslice: cap out of range");
 
   ret.__count = ilen;