A variety of linker issues (specifically missing symbol errors) don't
show up with static libraries, so it was a bit hard to track this down
without having something to link to. These have only been tested in
cross-compilation setups, so there may still be lurking horrors.
These are not handled properly when used as a dependency unless they
are attached to all of the artifacts because if a user only depends on
libssl, it doesn't include the headers attached to libcrypto.
This worked fine building libressl by itself, but it references the
wrong directory when executed as a dependency of another library. The
builder object seems to have its build root set correctly, so use
that.
