Fix parentheses in shift expression

Author: mattico

src/float/add.rs

@@ -157,7 +157,7 @@ macro_rules! add {
                 // need to shift the significand.
                 let shift = one - a_exponent;
                 let sticky = ((a_significand << (bits - shift).0 as usize).0 != 0) as <$ty as Float>::Int;
-                a_significand = a_significand >> (shift.0 | sticky) as usize;
+                a_significand = a_significand >> shift.0 as usize | Wrapping(sticky);
                 a_exponent = zero;
             }