[clang] [Driver][Sparc] Default to -mcpu=v9 for 32-bit Linux/sparc64 (PR #109278)

[Rainer Orth via cfe-commits]

rorth wrote:

Good, that considerably simplifies non-native testing:
- The original patch ignored the issue because I had no idea how to handle it.
- The first version of this one used the hack of checking `uname -v`.  While this works, it's still wrong since this checks the host distro, not the target one.
- It occured to me that one could use the vendor component of the target triple for this purpose.  Right now, only `SUSE` is used here, but it could be extended to Debian, Gentoo and others if need be.  AFAICS, the vendor field is usually just ignored.

https://github.com/llvm/llvm-project/pull/109278