linux_usbfs: Fix exit crash on Android

In commit "89b810ec Android: Add option LIBUSB_OPTION_WEAK_AUTHORITY
to support used in apk", we should also check weak_authority when
exiting the backend.

[dickens] Fixed whitespace

Closes #842

Signed-off-by: Mark Kuo <starryalley@gmail.com>
Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

libusb/os/linux_usbfs.c

diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 7175b35..4882c0f 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -415,6 +415,13 @@
 static void op_exit(struct libusb_context *ctx)
 {
 	UNUSED(ctx);
+
+#ifdef __ANDROID__
+	if (weak_authority) {
+		return;
+	}
+#endif
+
 	usbi_mutex_static_lock(&linux_hotplug_startstop_lock);
 	assert(init_count != 0);
 	if (!--init_count) {

libusb/version_nano.h

diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index b74033d..e7da9f6 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11596
+#define LIBUSB_NANO 11597