darwin: Fix compilation on macOS 10.9 and earlier

kUSBReEnumerateCaptureDeviceMask was introduced in the 10.10 SDK, so
compiling on 10.9 and earlier will fail with:

 os/darwin_usb.c: In function 'darwin_reenumerate_device':
 os/darwin_usb.c:1749:18: error: 'kUSBReEnumerateCaptureDeviceMask' undeclared (first use in this function); did you mean 'USBReEnumerateOptions'?
        options |= kUSBReEnumerateCaptureDeviceMask;
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                   USBReEnumerateOptions
 os/darwin_usb.c:1749:18: note: each undeclared identifier is reported only once for each function it appears in

Downstream report: https://trac.macports.org/ticket/63668

Closes #1023
diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index 10af647..15457f7 100644
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -1758,7 +1758,9 @@
   /* if we need to release capture */
   if (HAS_CAPTURE_DEVICE()) {
     if (capture) {
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= 101000
       options |= kUSBReEnumerateCaptureDeviceMask;
+#endif
     }
   } else {
     capture = false;
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 3c45733..1033492 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11670
+#define LIBUSB_NANO 11671