lavu/qsv: add log message for libmfx version

It is benefit to diagnose issues related to different libmfx version.
Signed-off-by: Zhong Li <zhong.li@intel.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavutil/hwcontext_qsv.c

@@ -1036,6 +1036,10 @@ static int qsv_device_derive_from_child(AVHWDeviceContext *ctx,
         goto fail;
     }
 
+    av_log(ctx, AV_LOG_VERBOSE,
+           "Initialize MFX session: API version is %d.%d, implementation version is %d.%d\n",
+           MFX_VERSION_MAJOR, MFX_VERSION_MINOR, ver.Major, ver.Minor);
+
     MFXClose(hwctx->session);
 
     err = MFXInit(implementation, &ver, &hwctx->session);