Create cros-specific unit tests.

Create infrastructure to allow cros-specific unit tests to be
created and executed.  Example .c unit tests are provided.
.c:  testcases/cros/unittests/cros_unittest_sample/cros_unittest_sample.c

Also create a cros test 'suite': runtest/cros_kernel_unittests.

Dependent CL creates a control.kernel_unittests that invokes
this suite wrapper.

To create a new test, create a new .c file within an existing
folder under cros/unittests or create a new folder with a
Makefile to contain new .c tests.  Each .c unittest simply
executes code and returns 0 for success and nonzero for failure.

To test:
-emerge-xxx autotest-tests-ltp
 (autotest-tests-ltp builds autotest-deps-ltp which builds the tests)
-run_remote_tests.sh ...  client/site_tests/kernel_LTP/control.kernel_unittests

BUG=chromium-os:36962
TEST=./run_remote_tests.sh --remote=... --use_emerged client/site_tests/kernel_LTP/control.sample
TEST=./run_remote_tests.sh --remote=... --use_emerged client/site_tests/kernel_LTP/control.kernel_unittests
TEST=./run_remote_tests.sh --remote=... --use_emerged client/site_tests/kernel_LTP/control.kernel_tests

CQ-DEPEND=I9d1c915edaac5abd82a29eef56906384f5b55345

Change-Id: I71fde5e6a90318b644b5b214477eb05f69f28cbb
Reviewed-on: https://gerrit.chromium.org/gerrit/45086
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Tested-by: Mike Truty <truty@chromium.org>
Commit-Queue: Mike Truty <truty@chromium.org>
20 files changed