This adds make install support to selftests. The basic usage is:

$ cd tools/testing/selftests
$ make install

That installs into tools/testing/selftests/install, which can then be
copied where ever necessary.

The install destination is also configurable using eg:

$ INSTALL_PATH=/mnt/selftests make install

The implementation uses two targets in the child makefiles. The first
"install" is expected to install all files into $(INSTALL_PATH).

The second, "emit_tests", is expected to emit the test instructions (ie.
bash script) on stdout. Separating this from install means the child
makefiles need no knowledge of the location of the test script.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

This adds a Make include file which most selftests can then include to
get the run_tests logic.

On its own this has the advantage of some reduction in repetition, and
also means the pass/fail message is defined in fewer places.

However the key advantage is it will allow us to implement install very
simply in a subsequent patch.

The default implementation just executes each program in $(TEST_PROGS).

We use a variable to hold the default implementation of $(RUN_TESTS)
because that gives us a clean way to override it if necessary, ie. using
override. The mount, memory-hotplug and mqueue tests use that to provide
a different implementation.

Tests are not run via /bin/bash, so if they are scripts they must be
executable, we add a+x to several.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>