[PATCH] clang-cl Add support for two MSVC conversion warnings

[Ehsan Akhgari]

>>! In D6041#7, @hans wrote:
> Do we really want to try supporting the individual MSVC warning flags?
> 
> It will never be a clean mapping anyway, and the diagnostics won't be very nice. For example, Clang won't print the MSVC style warning names when issuing a warning.
> 
> Can't you just use the same list of enabled/disabled warning that you use with Clang on other platforms?

Yeah, I suppose we could do that...  Should we can this patch, then?

http://reviews.llvm.org/D6041