[clang] [Sparc] Add flags to enable errata workaround pass for GR712RC and UT700 (PR #104742)

[Daniel Cederman via cfe-commits]

doac wrote:

Our UT700 and GR712RC processors are in active production and we have customers that for various reasons wants to use clang instead of gcc. To do that they need to use these workarounds to avoid certain sensitive code sequences (the same workarounds are already available in gcc). 
We have also developed some performance related patches for the Sparc backend, but it has been difficult to get them upstreamed as, as you say, few people are working on the Sparc backend. So instead we have provided our customers with custom versions of clang/llvm for the different operating systems that we support. 
In my experience these workarounds have been very easy to port forward, but the downside of not having them in mainline is that they are not included in 3:rd party tools that uses llvm nor in different operating system vendors custom toolchains.

https://github.com/llvm/llvm-project/pull/104742