factor::factor: Short-circuit the fallback to Pollard's rho

When the remainder is smaller than the max. entry in the table,
it is guaranteed to be prime.

src/uu/factor/src/factor.rs

@@ -100,7 +100,11 @@ fn factor(mut n: u64) -> Factors {
 
     let (f, n) = table::factor(n);
     factors *= f;
+
+    if n >= table::NEXT_PRIME {
         factors *= rho::factor(n);
+    }
+
     factors
 }