[Decode] Fix m_dst memory leak in VideoDECODEMJPEGBase_HW::Close()

At the start of each frame, m_dst is allocated to hold the decoded JPEG
data. After a successful decode, it is moved into m_dsts. Close() iterates
m_dsts and frees every entry. However, if the application stops mid-frame
(e.g. hits a frame-count limit), m_dst has been allocated but not yet
transferred into m_dsts. Close() skips it, leaving the allocation dangling.
The Debug CRT detects this leak on DLL unload and calls abort(), producing
STATUS_FATAL_APP_EXIT (exit code -1073740767 / 0xC0000421).

Add explicit delete[] m_dst; m_dst = nullptr; in Close() to cover
this path.

Author: yuanwade

_studio/mfx_lib/decode/mjpeg/src/mfx_mjpeg_dec_decode.cpp

@@ -1558,6 +1558,9 @@ mfxStatus VideoDECODEMJPEGBase_HW::Close(void)
         }
     }
 
+    delete[] m_dst;
+    m_dst = nullptr;
+
     memset(&m_stat, 0, sizeof(mfxDecodeStat));
 
     m_va = 0;