Fixes #9864. Make sure we wake up any sleepers the when we change fro…

…m the !readsallowed to the readsallowed state.

This usually happens implicitly simply due to the differences in the size of various buffers and read sizes. But that is a bit fragile and complicates tuning buffer sizes for better overall performance.

If you are experiencing the same timeout problem Jim Stichnoth has been experiencing, this should noticably improve your myth:// streaming performance.

mythtv/libs/libmythtv/ringbuffer.cpp

@@ -853,6 +853,8 @@ void RingBuffer::run(void)
 
         int used = bufferSize - ReadBufFree();
 
+        bool reads_were_allowed = readsallowed;
+
         if ((0 == read_return) || (numfailures > 5) ||
             (readsallowed != (used >= fill_min || ateof ||
                               setswitchtonext || commserror)))
@@ -909,7 +911,7 @@ void RingBuffer::run(void)
         else
         {
             // yield if we have nothing to do...
-            if (!request_pause &&
+            if (!request_pause && reads_were_allowed &&
                 (used >= fill_threshold || ateof || setswitchtonext))
             {
                 generalWait.wait(&rwlock, 50);