A commit between r227595 and r228444 broke tests on FreeBSD

Unfortunately the build was broken during this time so it's not
immediately clear which commit is at fault. The change caused more
than half of the tests to start timing out, and the issue is still
present.

Tests were "fine" here (8 failures in lldb-mi):
http://lab.llvm.org:8011/builders/lldb-x86_64-freebsd/builds/4189
last commit in range r227595

Build was broken here:
http://lab.llvm.org:8011/builders/lldb-x86_64-freebsd/builds/4190
first commit in range r227606, build failed

Build fixed here with tests timing out:
http://lab.llvm.org:8011/builders/lldb-x86_64-freebsd/builds/4228
last commit in range 228444

Is it possible to bisect the revision range?

I've been trying, but discovered that the issue only shows up when the
full test suite is run (i.e., ninja check-lldb) -- which makes for a
very slow process. If I run python dotest.py directly the tests do not
timeout. That's a big clue itself, and I'm starting to suspect it may
be a problem in FreeBSD that's somehow triggered by a change in the
range. The hunt continues...

It turns out this is a bug in FreeBSD's timeout(1), which gets stuck
if the child it is directly monitoring does not collect its own zombie
children. Presumably this condition now exists as a side effect of
some change. Even though we may want to investigate and avoid that in
LLDB or the tests, the underlying FreeBSD bug is what really needs to
be fixed.