[Media_api] Some #pragmas for Windows

[Roger Dannenberg]

Peter,
    I once tried to write code that would issue no warnings, and ended 
up going in circles -- changes that eliminated warnings on one platform 
would generate them on another. Sounds impossible, but a good example is 
one compiler knows that an exception or longjump jumps out of a 
function, so a following return stmt is unreachable code, whereas 
another compiler will know nothing about the exception and complain that 
you aren't returning a value. Anyway, I agree we should try to turn off 
warnings that are not warning us about real bugs. The trick is to be 
cross-platform and not turn off the possibility of getting new useful 
warnings in the future. If anyone knows the best way to do this or even 
a solid "best practices" approach, please let me know.

-Roger