#121 CD audio emulation not working with SDL 1.2

[Ignaz Forster]

It seems CDemu is not compatible with the audio playback mechanism of SDL 1.2 (https://www.libsdl.org/release/SDL-1.2.15/docs/html/cdrom.html), so a lot of games which use SDL for CD audio playback (or using a similar mechanism) will not play music as expected.

Steps to reproduce:
put an audio or mixed mode CD into the (virtual) drive
declare the virtual drive for SDL: export SDL_CDROM=/dev/sr3
* compile and run SDL's CD-ROM test application (https://hg.libsdl.org/SDL/file/cd46eb772bee/test/testcdrom.c).

Playback is aborted as soon as SDL_CDStatus is called in the test application, which in turn uses an ioctl querying CDROMSUBCHNL (https://hg.libsdl.org/SDL/file/cd46eb772bee/src/cdrom/linux/SDL_syscdrom.c#l450).

[Rok Mandeljc]

Thanks for the bug report!

I've reproduced the issue, and the cause appears to be the READ TOC/PMA/ATIP command implementation that was (incorrectly) interrupting the playback. I've pushed the fix to git master, and the test application seems to work for me now.