Remove comments about __int8 and friends from the mangler. Turns out we don't

actually have to implement them, since in modern versions of MSVC they're
aliases to the standard C types.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130509 91177308-0d34-0410-b5e6-96231b3b80d8