Remove fields from VexAbiInfo that only had relevance to the old AIX5
port: guest_ppc_sc_continues_at_LR and host_ppc32_regalign_int64_args.


git-svn-id: svn://svn.valgrind.org/vex@2904 8f6e269a-dfd6-0310-a8e1-e2731360e62c