Remove the CONFIG_CD macro, and enable faketracks unconditionally.

Remove the CONFIG_CD macro, and enable faketracks unconditionally.

All support for playing back CD-DA has been removed by leaving only the
SDL2 clients, and it is rather unlikely for CD-DA support to come back.
However while doing so, the CONFIG_CD macro was disabled in the makefile
but not the MSVC project, which broke faketracks (i.e. background music
via track003.ogg files) on Linux.

This change removes all #ifdefs for CONFIG_CD as well as its enablement
in the MSVC project, which is basically equivalent to having the feature
always being enabled.

Fixes background music in Quake with ripped music, Nexuiz, Xonotic, and
probably many other DP-based games. Also fixes Xonotic log spam about
gettime(GETTIME_CDTRACK).

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12466 d7cf8633-e32d-0410-b094-e92efae38249