[clang] [lld] [llvm] [RISCV] Make M imply Zmmul (PR #95070)

[Philip Reames via llvm-commits]

preames wrote:

Given the concern about breaking configurations w/no-integrated-as and older binutils, can someone summarize here which versions of binutils are known to work/not work after this change?  This will likely become the key search result for such breakage, and having it well documented for users seems critical.  

https://github.com/llvm/llvm-project/pull/95070