TpBaseClient: varargs_helper: allocate @features on the stack, not the heap
TpBaseClient: varargs_helper: allocate @features on the stack, not the heap

Based on a patch from Thomas Flueeli, who points out that this doesn't
work in MSVC 9.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib