Squashed 'external/devlib/' changes from d300b9e5..bf4e2421

bf4e2421 host: Use "sh -c" for background() like execute()
b1538fd1 host: remove unneeded concatenation
5b37dfc5 host: Remove sudo prompt from stderr in execute()
a9489827 host: Fix string literal

git-subtree-dir: external/devlib
git-subtree-split: bf4e24212917a4b3df6a6e885e2148a89ead0aa8