meson: improve subproject builds

Add meson subproject wrapfiles for all the openbmc projects we utilize
and fix the missing dependency for cereal.  There is still a missing
dependency for the `ldap.h` that prevents a full wrap-based build.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: If3a5836c3ff9a34d5624c60ac00c8fd46bfba20b
7 files changed