[WinEHPrepare] Don't rely on the order of IR

The IPToState table must be emitted after we have generated labels for
all functions in the table.  Don't rely on the order of the list of
globals.  Instead, utilize WinEHFuncInfo to tell us how many catch
handlers we expect to outline.  Once we know we've visited all the catch
handlers, emit the cppxdata.

llvm-svn: 234566