wgl: stw_pixelformat_get_info: correct type for index variable

Signed-off-by: Alon Levy <alevy@redhat.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
diff --git a/src/gallium/state_trackers/wgl/stw_pixelformat.c b/src/gallium/state_trackers/wgl/stw_pixelformat.c
index 96169e2..b0cd5ab 100644
--- a/src/gallium/state_trackers/wgl/stw_pixelformat.c
+++ b/src/gallium/state_trackers/wgl/stw_pixelformat.c
@@ -303,7 +303,7 @@
 const struct stw_pixelformat_info *
 stw_pixelformat_get_info( int iPixelFormat )
 {
-   int index;
+   unsigned index;
 
    if (iPixelFormat <= 0) {
       return NULL;