8205499: C1 temporary code buffers are not removed with -XX:+UseDynamicNumberOfCompilerThreads

Deallocate C1 code buffers in the compiler thread destructor.

Reviewed-by: neliasso, kvn, mdoerr

src/hotspot/share/runtime/thread.cpp

@@ -3298,6 +3298,11 @@ CompilerThread::CompilerThread(CompileQueue* queue,
 }
 
 CompilerThread::~CompilerThread() {
+  // Free buffer blob, if allocated
+  if (get_buffer_blob() != NULL) {
+    MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+    CodeCache::free(get_buffer_blob());
+  }
   // Delete objects which were allocated on heap.
   delete _counters;
 }