configure: remove usage of deprecated AC_HELP_STRING

This macro was replaced by AS_HELP_STRING. This commit updates the lingering deprecated call
with the new macro as used elsewhere in configure.ac.

Signed-off-by: Nathan Hjelm <hjelmn@google.com>
diff --git a/configure.ac b/configure.ac
index 4302b53..f6cf2f9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -171,7 +171,7 @@
 	AC_SEARCH_LIBS([clock_gettime], [rt], [], [], [])
 	AC_CHECK_FUNCS([pthread_setname_np])
 	AC_ARG_ENABLE([udev],
-		[AC_HELP_STRING([--enable-udev], [use udev for device enumeration and hotplug support (recommended) [default=yes]])],
+		[AS_HELP_STRING([--enable-udev], [use udev for device enumeration and hotplug support (recommended) [default=yes]])],
 		[use_udev=$enableval], [use_udev=yes])
 	if test "x$use_udev" = xyes; then
 		dnl system has udev. use it or fail!
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index a2c106c..94aba9b 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11646
+#define LIBUSB_NANO 11647