libfdt: fix build with Python 3

For some reason Python 3 seems to think it does not need to build
the library. Using the --force parameter makes sure that the library
gets built always. This is especially important since we move the
library in the next step of the Makefile, hence forcing a rebuild
every time the higher level Makefile triggers a rebuild is required
to make sure the library is always there.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Acked-by: Simon Glass <sjg@chromium.org>

lib/libfdt/setup.py

@@ -27,7 +27,7 @@ libfdt_module = Extension(
     extra_compile_args =  cflags
 )
 
-sys.argv = [progname, '--quiet', 'build_ext', '--inplace']
+sys.argv = [progname, '--quiet', 'build_ext', '--inplace', '--force']
 
 setup (name = 'libfdt',
        version = '0.1',