Fix AudioTrack cannot resume after underrun

Clear mPauseHwPending when updating track state on start().

Test: Manual
Bug: 187780419
Merged-In: I563162dd24ad2f56f898a239e8df848c7f80e122
Change-Id: I563162dd24ad2f56f898a239e8df848c7f80e122
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index 3e04804..3258689 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -1065,6 +1065,8 @@
             reset();
         }
 
+        // clear mPauseHwPending because of pause (and possibly flush) during underrun.
+        mPauseHwPending = false;
         if (state == PAUSED || state == PAUSING) {
             if (mResumeToStopping) {
                 // happened we need to resume to STOPPING_1