Actually remove the hack which was blocking the Borland-style attributes from
working, and add the missing attribute spellings. This brings _pascal,
_fastcall, _stdcall and _cdecl to life in -fborland-extensions mode.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173749 91177308-0d34-0410-b5e6-96231b3b80d8