Added Kconfig and makefiles to be able to build a Zephyr application
on Linux/gcc, and load via OpenOCD.
Validated by running the hello world, and philosophers microkernel
samples, and stepping through the code in gdb.
Jira: ZEP-1109
Change-Id: If5d3e7b1a8ecf5ecf6a00f147742b3bc5716190f
Signed-off-by: Gil Pitney <gil.pitney@linaro.org>