instaweb: add access+error logging for WEBrick

This allows WEBrick to support all the logging functionality
in a manner consistent with the other web servers.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
diff --git a/git-instaweb.sh b/git-instaweb.sh
index e69fb74..e6f6ecd 100755
--- a/git-instaweb.sh
+++ b/git-instaweb.sh
@@ -216,9 +216,15 @@
 	cat >"$fqgitdir/gitweb/$httpd.rb" <<EOF
 #!/usr/bin/env ruby
 require 'webrick'
+require 'logger'
 options = {
   :Port => $port,
   :DocumentRoot => "$root",
+  :Logger => Logger.new('$fqgitdir/gitweb/error.log'),
+  :AccessLog => [
+    [ Logger.new('$fqgitdir/gitweb/access.log'),
+      WEBrick::AccessLog::COMBINED_LOG_FORMAT ]
+  ],
   :DirectoryIndex => ["gitweb.cgi"],
   :CGIInterpreter => "$wrapper",
   :StartCallback => lambda do