AudioInput: remove use of the register keyword.
AudioInput: remove use of the register keyword.

Remove use of the register keyword.

Clang fails to build Mumble in C++11 mode if register is present.

LuAPi/mumble,Lartza/mumble,LuAPi/mumble,LuAPi/mumble,SuperNascher/mumble,SuperNascher/mumble,SuperNascher/mumble,SuperNascher/mumble,SuperNascher/mumble,Lartza/mumble,LuAPi/mumble,LuAPi/mumble,SuperNascher/mumble,LuAPi/mumble,Lartza/mumble,SuperNascher/mumble,SuperNascher/mumble,SuperNascher/mumble,Lartza/mumble,LuAPi/mumble,LuAPi/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,Lartza/mumble,LuAPi/mumble