[WinEH] Undo the effect of r249578 for 32-bit

The __CxxFrameHandler3 tables for 32-bit are supposed to hold stack
offsets relative to EBP, not ESP. I blindly updated the win-catchpad.ll
test case, and immediately noticed that 32-bit catching stopped working.

While I'm at it, move the frame index to frame offset WinEH table logic
out of PEI.  PEI shouldn't have to know about WinEHFuncInfo. I realized
we can calculate frame index offsets just fine from the table printer.

llvm-svn: 249618