Do not discard fragment allocator blocks multiple times.

discardBlock may be called multiple times on the same block.
We must not discard the block multiple times or we will corrupt
in-use memory accounting.

Change-Id: Ife9f3162785965a795dcf81887d4d447cc096e62


[ROCm/ROCR-Runtime commit: b9a0c1d313]

projects/rocr-runtime/runtime/hsa-runtime/core/util/simple_heap.h

@@ -300,6 +300,9 @@ template <typename Allocator> class SimpleHeap {
         (frag_map.rbegin()->first + frag_map.rbegin()->second.size <= base))
       return false;
 
+    // Is block already discarded?
+    if (frag_map.begin()->second.discard) return true;
+
     // Mark all fragments for discard and compute block size.  Removes freelist records for all
     // fragments in the block.
     size_t size = 0;