[llvm] [SDag][ARM][RISCV] Allow lowering CTPOP into a libcall (PR #101786)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

@mstorsjo 
Thanks for the information!
`isTargetWindows()` seems to be preferred for setting up libcall names ([example](https://github.com/llvm/llvm-project/blob/74b7abf15452574808834c0a08dd2af6bada2648/llvm/lib/Target/ARM/ARMISelLowering.cpp#L1268)), so I'll probably go with that interface just to be on the safe side.



https://github.com/llvm/llvm-project/pull/101786