lldb test: fix race condition
lldb test: fix race condition

When stepping or resuming, wait for asynchronous notification
to ensure the target has stopped before issuing more commands.
Previously there were just sleeps in the script.

jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor,jbush001/NyuziProcessor