Wasm llama2 tweaks (#309)

* Clean-up the llama2.c wasm example.

* Use a proper tokenizer.

candle-wasm-examples/llama2-c/src/lib.rs

@@ -1,28 +1,3 @@
-#![allow(dead_code)]
-
-pub const WITH_TIMER: bool = true;
-
-struct Timer {
-    label: &'static str,
-}
-
-impl Timer {
-    fn new(label: &'static str) -> Self {
-        if WITH_TIMER {
-            web_sys::console::time_with_label(label);
-        }
-        Self { label }
-    }
-}
-
-impl Drop for Timer {
-    fn drop(&mut self) {
-        if WITH_TIMER {
-            web_sys::console::time_end_with_label(self.label)
-        }
-    }
-}
-
 mod app;
 mod model;
 mod worker;