ISR: Work around a miscompilation for x64 when using VS2012.

That issue leaded the subtitles not to be shown at all when certain optimizations were turned on.
Cosmetics: Remove some do {...} while(0) loops.
ISR: Show all subtitles tracks in the Play > Subtitles menu.

All subtitles tracks available will be shown in the Play > Subtitles menu when using the internal subtitles renderer. That includes all the embedded tracks exhibited by the source filter and the external tracks.