[clang] [Clang][LoongArch] Generate _mcount instead of mcount (PR #65657)

[Lu Weining via cfe-commits]

https://github.com/SixWeining approved this pull request.

I have checked that glibc/sysdeps/loongarch/machine-gmon.h defines `_mcount`.

https://github.com/llvm/llvm-project/pull/65657