Remove core loading timeout
If target.preload-symbols is false, waiting for the process to "stop"
can take an arbitrarily long amount of time, because it will cause all
the debug info to be parsed (to compute the stop message showing the
function, its arguments, etc).
We were previously waiting for 10 seconds for the stop even to arrive,
which is a pretty long time, but it's not that hard to overcome with
huge debug info.
Since any arbitrary limit can be theoretically overcome with huge
debug_info and/or slow machine, and the stop even was sent 3 lines above
the wait, if we ever do not receive the stop even means we've got a bug
in lldb. Therefore, I remove the timeout on this wait completely.
No test because I don't know how to reproduce this without a
multi-gigabyte symbol file.
Reviewers: jingham, clayborg
Subscribers: aprantl, lldb-commits
Differential Revision: https://reviews.llvm.org/D63730