linux: fix gcc warnings when INVASIVE_GET_USAGE is defined.

libusb/hid.c

@@ -181,7 +181,7 @@ static uint32_t get_bytes(uint8_t *rpt, size_t len, size_t num_bytes, size_t cur
 static int get_usage(uint8_t *report_descriptor, size_t size,
                      unsigned short *usage_page, unsigned short *usage)
 {
-	int i = 0;
+	unsigned int i = 0;
 	int size_code;
 	int data_len, key_size;
 	int usage_found = 0, usage_page_found = 0;
@@ -509,6 +509,7 @@ struct hid_device_info  HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
 										get_usb_string(handle, desc.iProduct);
 
 #ifdef INVASIVE_GET_USAGE
+{
 							/*
 							This section is removed because it is too
 							invasive on the system. Getting a Usage Page
@@ -567,7 +568,7 @@ struct hid_device_info  HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
 										LOG("Couldn't re-attach kernel driver.\n");
 								}
 #endif
-
+}
 #endif // INVASIVE_GET_USAGE
 
 								libusb_close(handle);