Add META_MODE support.

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

diff --cc Makefile.depend
index 0000000000000000000000000000000000000000,0337134773d6c4ff8e378fd94d6d107edd30e4e1..1eb0f334cbe9fd3339129a4c082ee5102cf7ec32
mode 000000,100644..100644
--- /dev/null
--- 2/Makefile.depend
+++ b/Makefile.depend
@@@ -1,0 -1,19 +1,20 @@@
++# $FreeBSD$
+ # Autogenerated - do NOT edit!
+ 
+ DIRDEPS = \
+       gnu/lib/csu \
+       gnu/lib/libgcc \
+       include \
+       include/arpa \
+       include/rpc \
+       include/xlocale \
+       lib/${CSU_DIR} \
+       lib/libc \
+       lib/libcompiler_rt \
+ 
+ 
+ .include <dirdeps.mk>
+ 
+ .if ${DEP_RELDIR} == ${_DEP_RELDIR}
+ # local dependencies - needed for -jN in clean tree
+ .endif