time all builds and run

run

@@ -1,10 +1,11 @@
 #!/usr/bin/env python3
 
 import os
+import re
 import shlex
 import subprocess
 import sys
-import re
+import time
 
 import common
 
@@ -463,4 +464,8 @@ Run QEMU with VNC instead of the default SDL. Connect to it with:
 if __name__ == '__main__':
     parser = get_argparse()
     args = common.setup(parser)
-    sys.exit(main(args))
+    start_time = time.time()
+    exit_status = main(args)
+    end_time = time.time()
+    common.print_time(end_time - start_time)
+    sys.exit(exit_status)