Remove the parent output checks, as they make the test flaky while
serving no real purpose. If the parent crashed/hanged, it will never
resume the child and the test would fail anyway.
Add synchronization routines to ensure that Subprocess tests output
in a predictable order, and all test strings are output before the tests
terminate.
Differential Revision: https://reviews.llvm.org/D109495
Implement a new target.process.follow-fork-mode setting to control
LLDB's behavior on fork. If set to 'parent', the forked child is
detached and parent continues being traced. If set to 'child',
the parent is detached and child becomes traced instead.
Differential Revision: https://reviews.llvm.org/D100503
