vboot_host: Expose dynamic library

vboot_host is used by 32 platform2 packages, make it dynamic to:
- reduce disk space
- allow binary package caching:
  the package using vboot_host may not use or propagate the USE flag
  use to compile vboot_host, so their binary image could be used by
  mistake across boards.

Leave a static version for coreboot-utils, which compiles its own
version.

BUG=b:322516951
BRANCH=none
TEST=On brya, install local image, check crossystem works.
- unit tests
- run libcrossystem unit tests
- check library dependencies with:
readelf --dynamic /build/brya/usr/lib64/libvboot_host.so
- check coreboot-utils emerge with a static library.

Check libcrossystem uses libvboot_host.so with `ldd` command.
Check unit tests of libcrossystem pass.

Change-Id: I212bd7d9906821e4209f4c5abfd019bd786649d0
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/5255219
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2 files changed