hidapi/mac: replace sprintf uses with snprintf.

Reference issues:
-  libusb/hidapi#509
-  libusb/hidapi#511

(cherry picked from commit ae9119c)

src/hidapi/mac/hid.c

@@ -855,7 +855,7 @@ hid_device * HID_API_EXPORT hid_open_path(const char *path, int bExclusive)
 
 				/* Create the Run Loop Mode for this device.
 				 printing the reference seems to work. */
-				sprintf(str, "HIDAPI_%p", os_dev);
+				snprintf(str, sizeof(str), "HIDAPI_%p", os_dev);
 				dev->run_loop_mode = 
 				CFStringCreateWithCString(NULL, str, kCFStringEncodingASCII);