Even with --disable-git-update, ./configure tries updating the capstone
submodule instead of marking it "no"; this disables capstone submodule
if git update is disabled.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Thomas Huth <thuth@redhat.com>