By building the posix library as shared object with an ABI, we
effectively decouple posix-using programs from the library
implementation (which happens to depend on several os-level APIs such as
the VFS).
The file space demand for the object files when compiling core has grown.
Therefore, the ram_fs component runs out of memory and requests additional
memory from init. On OKL4, where the physical memory is limited by the
elfweaver bootstrap tool, there is no more slack memory after the donation
of 1G to noux.
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
