wined3d: Show fixme about unimplemented vertex processing once.

dlls/wined3d/state.c

@@ -1889,8 +1889,12 @@ static void state_ckeyblend(struct wined3d_context *context, const struct wined3
 
 static void state_swvp(struct wined3d_context *context, const struct wined3d_state *state, DWORD state_id)
 {
+    static int once;
     if (state->render_states[WINED3D_RS_SOFTWAREVERTEXPROCESSING])
-        FIXME("Software vertex processing not implemented.\n");
+    {
+        if (!once++)
+            FIXME("Software vertex processing not implemented.\n");
+    }
 }
 
 static void get_src_and_opr(DWORD arg, BOOL is_alpha, GLenum* source, GLenum* operand) {