Build both static and dynamic versions of futility.

In almost every case we want the dynamically linked version of futility,
because it's smaller and the openssl functions require it (they use
dl_open() to invoke the correct RSA libraries).

However, the AU shellball requires three futility functions (crossystem,
gbb_utility, and dump_fmap). Those pretty much have to be built statically,
because they run from the new rootfs and packing all the dynamic libraries
into the shellball is way too large and complicated.

This change prepares to build both futility (full featured) and futility_s
(just those functions). The scripts that create the AU shellball will
already choose futility_s from /build/$BOARD/.

BUG=chromium:224734
BRANCH=none
TEST=none
CQ-DEPEND=CL:47589

Nothing to test just yet. The AU shellball is currently broken (it uses the
dynamic version of futility and doesn't copy the symlinks anyway), so this
should have no effect. We just need to ensure that the _s version doesn't go
into any of the other images.

Change-Id: I60b8dcd17e135f12a0d29ddacfb9fe8275567c70
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/47466
4 files changed