[llvm] [RISCV] Make X5 allocatable for JALR on CPUs without RAS (PR #78417)

[Wang Pengcheng via llvm-commits]

wangpc-pp wrote:

> > > Ping for comments. :-)
> > 
> > 
> > If this didn't improve code size on llvm-test-suite, I think it just adds an extra configuration option for no benefit.
> 
> Result: [dtcxzyw/llvm-ci#1006 (comment)](https://github.com/dtcxzyw/llvm-ci/pull/1006#issuecomment-1926433112)

Thanks! The result is the same as my previous.

https://github.com/llvm/llvm-project/pull/78417