mumble_plugin.h: use _M_IX86 instead of (typo'd) _M_X86.
mumble_plugin.h: use _M_IX86 instead of (typo'd) _M_X86.

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