Squashed 'external/devlib/' changes from 86953449..f2b5f85d

f2b5f85d target/file_xfer: Fix incorrect method call
c0f26e53 target.py: Fix incorrect parameter name
1a02f77f target/pull: Use chmod from busybox
11768699 target: support threads in ps

git-subtree-dir: external/devlib
git-subtree-split: f2b5f85dab6561854121c91080a211f6c284ffa5