add an option to generate completely non-pic code, corresponding to what

gcc -static produces on PPC.  This is used for building kexts and other things.

With this, materializing the address of a global looks like:

        lis r2, ha16(L_H$non_lazy_ptr)
        la r3, lo16(L_H$non_lazy_ptr)(r2)

we're still emitting stubs for functions, which is wrong.  That is next.

llvm-svn: 24399