Add a process setting that keeps named threads running during
single-stepping operations. Some programs install in-process Mach
exception handler threads that must continue running to forward
exceptions. When lldb single-steps and suspends all other threads, these
handler threads stall, potentially causing a deadlock if the stepped
instruction raises an exception.
The new `target.process.always-run-thread-names` setting accepts a list
of thread name strings. In `ThreadList::WillResume`, threads whose names
match an entry in this list are resumed with `eStateRunning` instead of
`eStateSuspended`, ensuring they appear in vCont packets even during
single-thread stepping.
rdar://175038920
9332051a2e