worker: support more return types in posix worker
This allows us to return things that aren't tuple(int, str) from worker
functions. I wanted to use marshal instead of pickle, but it seems to read from
the pipe in non-blocking mode, which means it stops before it sees the results.
The windows worker already supports arbitrary return values without
serialization, because it uses threads instead of subprocesses.
Differential Revision: https://phab.mercurial-scm.org/D3845
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}