[WinEH] Use llvm.x86.seh.recoverfp in WinEHPrepare

Don't pattern match for frontend outlined finally calls on non-x64
platforms. The 32-bit runtime uses a different funclet prototype.  Now,
the frontend is pre-outlining the finally bodies so that it ends up
doing most of the heavy lifting for variable capturing. We're just
outlining the callsite, and adapting the frameaddress(0) call to line up
the frame pointer recovery.

llvm-svn: 241186