Squashed 'vendor/compat-5.2/' changes from a37929f..10c9c78

10c9c78 added LUA_OK define
1f85b37 string.format escapes control characters for %q now

git-subtree-dir: vendor/compat-5.2
git-subtree-split: 10c9c7836435f6a89c464bbd7a9b782286281cb7
vendor/compat-5.2: Pull in new code (includes LUA_OK) define