Bugfix: --disable-other-drivers should not force libusb to be unused

configure.ac

@@ -586,7 +586,7 @@ libusb_include_path=""
 AC_ARG_WITH([libusb],
 	[AC_HELP_STRING([--without-libusb],[Compile using libusb (default enabled)])],
 	[want_libusb=$withval],
-	[want_libusb=$ddauto]
+	[want_libusb=auto]
 	)
 if test "x$want_libusb" != "xno"; then
 PKG_CHECK_MODULES([LIBUSB], [libusb-1.0],[