Squashed 'external/devlib/' changes from 4c8f2430..6f42f67e

6f42f67e target: Ensure we use installed binaries
ae7f01fd target: Use root if available when determine number of cpus
b5f36610 trace/perf: Soften POSIX signal for termination

git-subtree-dir: external/devlib
git-subtree-split: 6f42f67e957fc883d42b0a23d512d604204d0e72