Add AltiVec and FPU support to the Context_Control in case we use the
e6500 multilib.
Add PPC_MULTILIB_ALTIVEC and PPC_MULTILIB_FPU multilib defines. Add
non-volatile AltiVec and FPU context to Context_Control. Add save/restore of
non-volatile AltiVec and FPU to _CPU_Context_switch(). Add save/restore
of volatile AltiVec and FPU context to the exception code. Adjust data
cache optimizations for the new context and cache line size.
3e2647a714