Fix ARM SjLj-EH dispatch setup code. <rdar://problem/10444602>

Fix ARM SjLj-EH dispatch setup code. <rdar://problem/10444602>

The EmitBasePointerRecalculation function has 2 problems, one minor and one
fatal.  The minor problem is that it inserts the code at the setjmp
instead of in the dispatch block.  The fatal problem is that at the point
where this code runs, we don't know whether there will be a base pointer,
so the entire function is a no-op.  The base pointer recalculation needs to
be handled as it was before, by inserting a pseudo instruction that gets
expanded late.

Most of the support for the old approach is still here, but it no longer
has any connection to the eh_sjlj_dispatchsetup intrinsic.  Clean up the
parts related to the intrinsic and just generate the pseudo instruction
directly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144781 91177308-0d34-0410-b5e6-96231b3b80d8