Unfortunately filemon/meta mode tracks all indirect dependencies here
since ld(1) is reading libelf when linking in libkvm. Churn would be
reduced if this was able to be limited to direct dependencies.
Sponsored by: EMC / Isilon Storage Division
Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.
Still need to add real targets under targets/ to build packages.
Differential Revision: D2796
Reviewed by: brooks imp
