[llvm] DAG: Use RuntimeLibcalls to legalize vector frem calls (PR #170719)

[Matt Arsenault via llvm-commits]

arsenm wrote:

Reduced:
```
define <2 x double> @frem_v2f64(<2 x double> %a, <2 x double> %b) #0 {
  %frem = frem <2 x double> %a, %b
  ret <2 x double> %frem
}

attributes #0 = { "target-features"="+simd128" }
```

It's failing on unsupported handling of the Libcall action for vector calls. I think 6ad41bcc498b7c186ceb54616c3697fc9873c04a is the more likely trigger point 

https://github.com/llvm/llvm-project/pull/170719