[llvm] [memprof] Add YAML-based deserialization for MemProf profile (PR #117829)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

> @kazutakahirata I'm seeing MSVC build warnings due to [e98396f](https://github.com/llvm/llvm-project/commit/e98396f4846bfcaabe2c2ee568aab4b78655f307):
> 
> ```
> E:\llvm\llvm-project\llvm\lib\ProfileData\MemProfReader.cpp(56): error C2220: the following warning is treated as an error
> E:\llvm\llvm-project\llvm\lib\ProfileData\MemProfReader.cpp(56): warning C4189: '<structured binding>': local variable is initialized but not referenced
> ```

Thank you for reporting this to me!  I've reproduced the problem with a small test case on Compiler Explorer.  I'll put `(void)var;`.

https://github.com/llvm/llvm-project/pull/117829