[scudo] Apply the min release threshold to the group

For the block smaller than a page size, one block is unlikely to
introduce more unused pages (at most 2 if it acrosses the page boundary
and both touched pages are unused). So it's better to apply the
threshold to reduce the time of scanning groups that can't release any
new pages.

Author: ChiaHungDuan

compiler-rt/lib/scudo/standalone/primary64.h

@@ -1492,6 +1492,8 @@ template <typename Config> class SizeClassAllocator64 {
       }
 
       const uptr PushedBytesDelta = BytesInBG - BG->BytesInBGAtLastCheckpoint;
+      if (PushedBytesDelta < getMinReleaseAttemptSize(BlockSize))
+        continue;
 
       // Given the randomness property, we try to release the pages only if the
       // bytes used by free blocks exceed certain proportion of group size. Note