test_reservation(), test_double_pair_instrs(): Fix broken inline assembly 
causing segfaults with gcc-4.7.  The inline assembly still isn't right,
but it's better than it was before.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13279 a5019735-40e9-0310-863c-91ae7b9d1cf9