Fix compile error caused by a breaking change to the compiler

rust-lang/rust#39207

Author: jminer

src/lib.rs

@@ -25,19 +25,19 @@ fn get_thread_id() -> isize {
 }
 
 macro_rules! impl_control_traits {
-    ($control:ident) => {
-        unsafe impl Control for ::$control {
+    ($control:path) => {
+        unsafe impl Control for $control {
             fn handle(&self) -> *mut Ihandle {
                 assert!(!self.0.get().is_null(), "attempted to use destroyed control");
                 ::check_thread();
                 self.0.get()
             }
         }
 
-        unsafe impl UnwrapHandle for ::$control {
+        unsafe impl UnwrapHandle for $control {
             fn try_unwrap_handle(self) -> Result<*mut Ihandle, Self> {
                 assert!(!self.0.get().is_null(), "attempted to use destroyed control");
-                self.0.try_unwrap().map_err(|handle_rc| ::$control(handle_rc))
+                self.0.try_unwrap().map_err(|handle_rc| $control(handle_rc))
             }
         }
     };