ui/vnc-enc-tight: remove switch and have single return

When enabling the sanitizer build it will complain about control
reaching a non-void function. Normally the compiler should detect that
there is only one possible exit given a static VNC_SERVER_FB_BYTES.

As we always expect a static VNC_SERVER_FB_BYTES I've added a compile
time assert and just called the sub-function directly.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/vnc-enc-tight.c

@@ -707,10 +707,8 @@ check_solid_tile32(VncState *vs, int x, int y, int w, int h,
 static bool check_solid_tile(VncState *vs, int x, int y, int w, int h,
                              uint32_t* color, bool samecolor)
 {
-    switch (VNC_SERVER_FB_BYTES) {
-    case 4:
-        return check_solid_tile32(vs, x, y, w, h, color, samecolor);
-    }
+    QEMU_BUILD_BUG_ON(VNC_SERVER_FB_BYTES != 4);
+    return check_solid_tile32(vs, x, y, w, h, color, samecolor);
 }
 
 static void find_best_solid_area(VncState *vs, int x, int y, int w, int h,