svga: improve check for 3D compressed textures

This is basically a a respin of f1dfcf4bce
per Jose's suggestion.

Just set the SVGA3dSurfaceFormatCaps flags for 3D and cube textures
when checking the texture format capabilities.  This will filter out
unsupported combinations like 3D+DXT.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/gallium/drivers/svga/svga_screen.c

@@ -447,11 +447,6 @@ svga_is_format_supported( struct pipe_screen *screen,
       }
    }
    
-   if (target == PIPE_TEXTURE_3D && util_format_is_compressed(format)) {
-      /* we don't support compressed 3D textures at this time */
-      return FALSE;
-   }
-
    /*
     * Query the host capabilities.
     */
@@ -469,6 +464,13 @@ svga_is_format_supported( struct pipe_screen *screen,
       mask.texture = 1;
    }
 
+   if (target == PIPE_TEXTURE_CUBE) {
+      mask.cubeTexture = 1;
+   }
+   if (target == PIPE_TEXTURE_3D) {
+      mask.volumeTexture = 1;
+   }
+
    return (caps.value & mask.value) == mask.value;
 }