Test error handling for mfsession_Start when a source fails
at different stages.

I fixed this issue in ad05f33d, but a40973f2 regressed this again. I
was carrying a patch for quite a while, feeling dejavu.

According to boost they are available since MSVC 2015. I don't have old
versions of msvc hanging around, and we don't put much value in keeping
old versions working, so just use them unconditionally.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=11436

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=51311

This matches the declaration with official documentation and fixes
the following two compiler errors in apitrace project.

d3d9trace.cpp:28469:59: error: invalid conversion from 'const DXVA2_ConfigPictureDecode*' to 'DXVA2_ConfigPictureDecode*' [-fpermissive]
d3d9trace.cpp:28194:65: error: invalid conversion from 'void*' to 'IUnknown*' [-fpermissive]
Signed-off-by: Biswapriyo Nath <nathbappai@gmail.com>

With the changes from 0b8db612.