Fix DXVA status for some decoders after 4a79186.

Checking status only once is not reliable.
Even LAV Video Decoder can disable HW decoding on fly except DXVA Native mode.

Fixes #3881
Show tooltip with H/W decoder name in status bar.

Fixes #3873
Statusbar: fix some visual glitches

Fixes #2870
Merge pull request #124 from kasper93/dxva_status

H/W acceleration status changes.