tools: add favicon to the html produced by fast.v

Author: spytheman

cmd/tools/fast/header.html

@@ -4,6 +4,9 @@
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>Is V still fast?</title>
+<link rel="icon" type="image/x-icon" sizes="32x32" href="favicon_32x32.ico">
+<link rel="icon" type="image/x-icon" sizes="16x16" href="favicon_16x16.ico">
+<link rel="icon" type="image/x-icon" href="favicon.ico">
 <style>
 *, body {
 	font-family: Menlo, Monospace, 'Courier New';