r216489 - Update for llvm api change

[Rafael Espíndola]

>>      llvm::SMDiagnostic Err;
>> -    TheModule = parseIR(MainFile, Err, *VMContext);
>> +    TheModule = parseIR(MainFile->getMemBufferRef(), Err, *VMContext);
>
>
> Should we make MemoryBufferRef implicitly constructible from a MemoryBuffer?
> (that way you could just write "parseIR(*MainFile, ... ") Similar to
> ArrayRef.
>

I personally don't like implicit conversions, so I would avoid this
one unless we start seeing a lot of getMemBufferRef.

Cheers,
Rafael