Don't forward declare functions with "inline" in headers

Don't mark function definitions in headers with "inline" - it causes
compile warnings on gcc v5.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Acked-by: Paul Menzel <paulepanter@sourceforge.net>
diff --git a/src/hw/usb-hid.h b/src/hw/usb-hid.h
index ef34e79..fd7b8f8 100644
--- a/src/hw/usb-hid.h
+++ b/src/hw/usb-hid.h
@@ -4,10 +4,10 @@
 // usb-hid.c
 struct usbdevice_s;
 int usb_hid_setup(struct usbdevice_s *usbdev);
-inline int usb_kbd_active(void);
-inline int usb_kbd_command(int command, u8 *param);
-inline int usb_mouse_active(void);
-inline int usb_mouse_command(int command, u8 *param);
+int usb_kbd_active(void);
+int usb_kbd_command(int command, u8 *param);
+int usb_mouse_active(void);
+int usb_mouse_command(int command, u8 *param);
 void usb_check_event(void);