egl/dri2: Drop some pointless ifdeffery

The fallback is already `return true;`

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7864>

src/egl/drivers/dri2/egl_dri2.c

@@ -183,16 +183,6 @@ dri_is_thread_safe(void *loaderPrivate)
       return false;
 #endif
 
-#ifdef HAVE_XCB_PLATFORM
-   if (display->Platform == _EGL_PLATFORM_XCB)
-      return true;
-#endif
-
-#ifdef HAVE_WAYLAND_PLATFORM
-   if (display->Platform == _EGL_PLATFORM_WAYLAND)
-      return true;
-#endif
-
    return true;
 }