Amends the following compiler warnings:

 ```
 NXwindow.c: In function ‘nxagentClearSplash’:
 NXwindow.c:342:12: warning: variable ‘h’ set but not used [-Wunused-but-set-variable]
      int w, h;
             ^
 NXwindow.c:342:9: warning: variable ‘w’ set but not used [-Wunused-but-set-variable]
      int w, h;
          ^
 ```