openvmtools: remove unnecessary C flag

Since commit 8bec0a1a
the -Wno-unused-local-typedefs CFLAG in not needed.

Signed-off-by: Karoly Kasza <kaszak@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>