tests: add weston test-suite files

Add Weston's test runner
test-runner: make it compileable

replace unknown variable (program_invocation_short_name) for program
name (argv[0])
test-plugin: add support for running tests

Run tests that are given in MUTTER_WAYLAND_TEST evnironment variable.
The tests are absolute paths to the binaries and are space separated.
If no tests are passed, leave mutter running in order that user wants
do manual testing.