fixed compilation of ucc with clang

git-svn-id: https://svn.code.sf.net/p/exult/code/exult/trunk@7448 67c084eb-e78b-48f3-b8e7-bfa43f95ef20
While cross compiling you can add a native built expack and head2data to the
path or point to them vie EXPACK and HEAD2DATA environment variables. This
should make cross compiling for iOS and other targets less annoying.

git-svn-id: https://svn.code.sf.net/p/exult/code/exult/trunk@7451 67c084eb-e78b-48f3-b8e7-bfa43f95ef20
added a check for true mt32, fakemt32 and mt32emu
and made sure the background sfx tracks 
are only played by those. Fixes bug #1872
Thanks to wjp for his help

git-svn-id: https://svn.code.sf.net/p/exult/code/exult/trunk@7452 67c084eb-e78b-48f3-b8e7-bfa43f95ef20