find headers regardless of directory layout in vm-depends definition
modify (THREAD_)RUNTIME_ARRAY definition so RUNTIME_ARRAY_BODY must be used

Previously, if you forgot to use RUNTIME_ARRAY_BODY to reference an
array declared with (THREAD_)RUNTIME_ARRAY, you wouldn't get a
compiler error until you tried to build on e.g. MSVC, where
runtime-sized stack arrays aren't supported.  This change ensures you
find out regardless of what compiler you're using, which ought to
protect us from regressions going forward.
Merge branch 'master' of github.com:ReadyTalk/avian

Conflicts:
	makefile