Make the tor binary executable on all platforms.

Also, do it to the binary, not to the zip file, on Windows.  Not sure
how this worked before!  Maybe the file got truncated rather than
replaced?

Auditors:
@diracdeltas
@jumde

Test Plan:

Launch Brave.  New private tab.  Turn on Tor.  Visit
https://check.torproject.org and confirm Tor is working.

tools/package_tor.js

@@ -60,8 +60,9 @@ execute([cmd], '', (err) => {
   console.log('tor binary checksum matches')
   // unzip on windows
   if (isWindows) {
-    fs.chmodSync(torBinary, 0o755)
     fs.createReadStream(torBinary).pipe(unzip.Extract({ path: torPath }))
   }
+  // make it executable
+  fs.chmodSync(torBinary, 0o755)
   console.log('done')
 })