tools/usbwait/: new tool to wait for a USB device to appear

- usbwait/usbwait.c: update the USB device tree until the specified
  device is detected
- usbwait/Makefile: build usbwait (host only)
- Makefile (DIRS, BEN_DIRS, upload): separated subdirectories with tools
  that can run on the Ben from those that can't
- Makefile (DIRS): added usbwait/

tools/usbwait/Makefile

@@ -0,0 +1,40 @@
+#
+# usbwait/Makefile - Wait for an USB device to appear
+#
+# Written 2011 by Werner Almesberger
+# Copyright 2011 Werner Almesberger
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+
+
+MAIN = usbwait
+
+ifeq ($(TARGET),)
+TARGET = host
+endif
+
+ifeq ($(TARGET),host)
+
+include ../Makefile.common
+
+else
+
+.PHONY:		all install uninstall clean spotless
+
+all:
+
+install:
+
+uninstall:
+
+clean:
+		rm -f $(MAIN).o
+
+spotless:	clean
+		rm -f $(MAIN)
+
+endif