Benchmark for cha random too.

benchmarks/charand.c

@@ -0,0 +1,16 @@
+#include "chacha20.c"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(void)
+{
+    uint64_t N = 1000000;
+    uint8_t* buf = malloc(N);
+    const uint8_t key[32] = {0};
+    const uint8_t nonce[16] = {0};
+    for (uint64_t i = 0; i < 1000; ++i)
+    {
+        cha_generate(buf, N, key, nonce);
+    }
+    free(buf);
+}