Prefix hex values with 0x in core.c and os/openbsd_usb.c

It makes it clear from debug logs, that values are in hex,
without a need to check the source code.

Closes #832

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>
diff --git a/libusb/core.c b/libusb/core.c
index 051b4f7..701f981 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -1795,7 +1795,7 @@
 int API_EXPORTED libusb_clear_halt(libusb_device_handle *dev_handle,
 	unsigned char endpoint)
 {
-	usbi_dbg("endpoint %x", endpoint);
+	usbi_dbg("endpoint 0x%x", endpoint);
 	if (!usbi_atomic_load(&dev_handle->dev->attached))
 		return LIBUSB_ERROR_NO_DEVICE;
 
diff --git a/libusb/os/openbsd_usb.c b/libusb/os/openbsd_usb.c
index e05610e..6ba47b4 100644
--- a/libusb/os/openbsd_usb.c
+++ b/libusb/os/openbsd_usb.c
@@ -565,7 +565,7 @@
 	dpriv = usbi_get_device_priv(transfer->dev_handle->dev);
 	setup = (struct libusb_control_setup *)transfer->buffer;
 
-	usbi_dbg("type %x request %x value %x index %d length %d timeout %d",
+	usbi_dbg("type 0x%x request 0x%x value 0x%x index %d length %d timeout %d",
 	    setup->bmRequestType, setup->bRequest,
 	    libusb_le16_to_cpu(setup->wValue),
 	    libusb_le16_to_cpu(setup->wIndex),
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 6e25f2d..903cd6f 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11593
+#define LIBUSB_NANO 11594