Summary:
MSDN says that fastcall, stdcall, thiscall, and vectorcall are all
accepted but ignored on ARM and X64.
https://msdn.microsoft.com/en-us/library/984x0h58.aspx
MSDN also says cdecl is also accepted and typically ignored
This patch brings ARM in line with how we ignore them for X64
Reviewers: rnk
Subscribers: compnerd, cfe-commits
Differential Revision: http://reviews.llvm.org/D12034
llvm-svn: 245076