got an IPC stress tester that actually works

I had to write it in C++ to get it to actually exercise processing power
instead of disk IO. Also, I had to tweak some timeouts etc in some of
the tests to avoid random false failures.
diff --git a/aos/common/condition_test.cc b/aos/common/condition_test.cc
index ddc12d5..49112bc 100644
--- a/aos/common/condition_test.cc
+++ b/aos/common/condition_test.cc
@@ -40,7 +40,7 @@
   Shared *const shared_;
 
   void Settle() {
-    time::SleepFor(::Time::InSeconds(0.009));
+    time::SleepFor(::Time::InSeconds(0.008));
   }
 };
 
@@ -56,7 +56,7 @@
 
   // This amount gets added to any passed in delay to make the test repeatable.
   static constexpr ::Time kMinimumDelay = ::Time::InSeconds(0.015);
-  static constexpr ::Time kDefaultTimeout = ::Time::InSeconds(0.06);
+  static constexpr ::Time kDefaultTimeout = ::Time::InSeconds(0.09);
 
   // delay is how long to wait before doing action to condition.
   // timeout is how long to wait after delay before deciding that it's hung.