[UR][L0] Release parent of sub-buffer when sub-buffer dies

This commit fixes an issue where the sub-buffer object in the L0 V1
adapter would not release its retained parent, causing leaks.

Signed-off-by: Larsen, Steffen <steffen.larsen@intel.com>

Author: Larsen, Steffen

unified-runtime/source/adapters/level_zero/memory.cpp

@@ -2336,6 +2336,11 @@ _ur_buffer::_ur_buffer(ur_context_handle_t Context, size_t Size,
   LastDeviceWithValidAllocation = Device;
 }
 
+_ur_buffer::~_ur_buffer() {
+  if (isSubBuffer())
+    ur::level_zero::urMemRelease(SubBuffer->Parent);
+}
+
 ur_result_t ur_mem_handle_t_::getZeHandle(char *&ZeHandle, access_mode_t mode,
                                           ur_device_handle_t Device,
                                           const ur_event_handle_t *phWaitEvents,

unified-runtime/source/adapters/level_zero/memory.hpp

@@ -127,6 +127,8 @@ struct _ur_buffer final : ur_mem_handle_t_ {
   _ur_buffer(ur_context_handle_t Context, size_t Size,
              ur_device_handle_t Device, char *ZeMemHandle, bool OwnZeMemHandle);
 
+  ~_ur_buffer();
+
   // Returns a pointer to the USM allocation representing this PI buffer
   // on the specified Device. If Device is nullptr then the returned
   // USM allocation is on the device where this buffer was used the latest.