Log when binder thread pool is starved

Log when the number of threads executing binder commands is equal to the
maximium size of the thread pool for >100ms.

Bug: 28201939
Change-Id: I892863d8a81c06e362d4ae18ab08485fdec3c0bb
diff --git a/include/binder/ProcessState.h b/include/binder/ProcessState.h
index f9edc2a..64cf72e 100644
--- a/include/binder/ProcessState.h
+++ b/include/binder/ProcessState.h
@@ -91,6 +91,8 @@
             size_t              mExecutingThreadsCount;
             // Maximum number for binder threads allowed for this process.
             size_t              mMaxThreads;
+            // Time when thread pool was emptied
+            int64_t             mStarvationStartTimeMs;
 
     mutable Mutex               mLock;  // protects everything below.