launch: don't add a drive twice 1. Change the g->path to restore a absolute path instead of the mixed. 2. Check that if the adding drive is duplicated with the added drive. Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com> RWMJ: - Make sure abs_path is NULL before it is assigned, so freeing it will work along the error path. - Fix the test which added /dev/null multiple times.
tests: Rename capitests -> tests/c-api.