Add nominal support for 'shave' target.

This change passes through C and assembler jobs to Movidius tools by
constructing commands which are the same as ones produces by the examples
in the SDK. But rather than reference MV_TOOLS_DIR to find tools,
we will assume that binaries are installed wherever the Driver would
find its native tools. Similarly, this change assumes that -I options
will "just work" based on where SDK headers get installed, rather than
baking into the Driver some magic paths.

Differential Revision: http://reviews.llvm.org/D10440

llvm-svn: 240134