Allow building kati & makeparallel with soong

This uses far fewer hacks in order to build these host tools, but will
require more libraries(libc++,etc) from unbundled and stripped down
branches.

Once this becomes the only option, all builds will happen after soong
runs. Then the toolchain / global cflags information will be able to be
moved from make to soong (and exported back to make).

Change-Id: I270b1d92bcef28a96fbc3ec9910d9bd0c101ac0f