improve readability of is_power_of_two

Author: tspiteri

src/libcore/num/mod.rs

@@ -3750,7 +3750,7 @@ assert!(!10", stringify!($SelfT), ".is_power_of_two());", $EndFeature, "
             #[stable(feature = "rust1", since = "1.0.0")]
             #[inline]
             pub const fn is_power_of_two(self) -> bool {
-                ((self.wrapping_sub(1)) & self == 0) & !(self == 0)
+                self.count_ones() == 1
             }
         }