fixes issue 1098
fixes issue 1098

As it looks tricky to shift the wow64 syscall setup, I did a quick fix and
switched the TEB-as-stack to use DR's 4 scratch slots rather than the TLS
field.

git-svn-id: ed337ca7cdb08c0ba29d8fe58632bb7686892c2d@1961 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6

rnk/dynamorio,rnk/dynamorio,rnk/dynamorio,rnk/dynamorio,rnk/dynamorio