libenca: Move build host tool to PRE_BUILD_HOOKS
The make_hash host tool, should be built during a PRE_BUILD_HOOKS and
not a POST_CONFIGURE_HOOKS.
Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>