[llvm] Treat ';' and '\n' as assembly instruction separators in collectAsmInstrs (PR #149365)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> This would break Mach-O, which uses `;` as a comment marker.
> 
> See `CommentString = ";";` in MCAsmInfo.cpp files. Unfortunately, IR cannot depend on MC..

But we know the object format from the triple. Most of the properties in MCAsmInfo probably should be triple functions 

https://github.com/llvm/llvm-project/pull/149365