Kbuild: Build minimal libc as a static library.

This commit changes the way libc is built.
Instead of building a hierarchy of objects linked into the
microkernel, libc minimal is built as a static library and
linked against the microkernel binary.
The location of the libc is configurable with the variable
KLIBC_DIR. This gives the flexibility to build against a
different libc other than minimal.

Change-Id: I9c0b6a684a9f3b407861aa387727c45eceb269c4
Signed-off-by: Juan Manuel Cruz <juan.m.cruz.alcaraz@linux.intel.com>
8 files changed