std::rand: lengthen the RNG benchmarks.

This makes them more representative, as the `bh.iter` is a smaller
percentage of the total time.

Author: huonw

src/libstd/rand/mod.rs

@@ -970,41 +970,53 @@ mod bench {
     use extra::test::BenchHarness;
     use rand::*;
     use mem::size_of;
+    use iter::range;
+    use option::{Some, None};
+
+    static N: u64 = 100;
 
     #[bench]
     fn rand_xorshift(bh: &mut BenchHarness) {
         let mut rng = XorShiftRng::new();
         do bh.iter {
-            rng.gen::<uint>();
+            for _ in range(0, N) {
+                rng.gen::<uint>();
+            }
         }
-        bh.bytes = size_of::<uint>() as u64;
+        bh.bytes = size_of::<uint>() as u64 * N;
     }
 
     #[bench]
     fn rand_isaac(bh: &mut BenchHarness) {
         let mut rng = IsaacRng::new();
         do bh.iter {
-            rng.gen::<uint>();
+            for _ in range(0, N) {
+                rng.gen::<uint>();
+            }
         }
-        bh.bytes = size_of::<uint>() as u64;
+        bh.bytes = size_of::<uint>() as u64 * N;
     }
 
     #[bench]
     fn rand_isaac64(bh: &mut BenchHarness) {
         let mut rng = Isaac64Rng::new();
         do bh.iter {
-            rng.gen::<uint>();
+            for _ in range(0, N) {
+                rng.gen::<uint>();
+            }
         }
-        bh.bytes = size_of::<uint>() as u64;
+        bh.bytes = size_of::<uint>() as u64 * N;
     }
 
     #[bench]
     fn rand_std(bh: &mut BenchHarness) {
         let mut rng = StdRng::new();
         do bh.iter {
-            rng.gen::<uint>();
+            for _ in range(0, N) {
+                rng.gen::<uint>();
+            }
         }
-        bh.bytes = size_of::<uint>() as u64;
+        bh.bytes = size_of::<uint>() as u64 * N;
     }
 
     #[bench]