[compiler-rt] [compiler-rt] Add a prefix on the windows mmap symbols (PR #78037)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> > For Windows, the compiler-rt profile library contains a polyfill reimplementation of the mmap family of functions.
> 
> Perhaps add https://reviews.llvm.org/D15830 to the description?

Sorry - I forgot about amending this in, I only noticed it now after merging :-(

https://github.com/llvm/llvm-project/pull/78037