Keyboard.c: fix three memory leaks

==12976==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 6 byte(s) in 1 object(s) allocated from:
    #0 0x7f510b3ac810 in strdup (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3a810)
    #1 0x559ca29c5035 in nxagentKeyboardProc /home/uli/work/nx/ArcticaProject/nx-libs/nx-X11/programs/Xserver/hw/nxagent/Keyboard.c:866
    #2 0x7a29bff07  (<unknown module>)

Direct leak of 1 byte(s) in 1 object(s) allocated from:
    #0 0x7f510b3ac810 in strdup (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3a810)
    #1 0x559ca29c509a in nxagentKeyboardProc /home/uli/work/nx/ArcticaProject/nx-libs/nx-X11/programs/Xserver/hw/nxagent/Keyboard.c:870
    #2 0x7a29bff07  (<unknown module>)

Direct leak of 1 byte(s) in 1 object(s) allocated from:
    #0 0x7f510b3ac810 in strdup (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3a810)
    #1 0x559ca29c507f in nxagentKeyboardProc /home/uli/work/nx/ArcticaProject/nx-libs/nx-X11/programs/Xserver/hw/nxagent/Keyboard.c:869
    #2 0x7a29bff07  (<unknown module>)

SUMMARY: AddressSanitizer: 8 byte(s) leaked in 3 allocation(s).

nx-X11/programs/Xserver/hw/nxagent/Keyboard.c

@@ -945,6 +945,10 @@ N/A
         {
           NXShadowInitKeymap(&(pDev->key->curKeySyms));
         }
+
+	free(rules);
+	free(variant);
+	free(options);
       }
 
       if (xkb)