[llvm] RuntimeLibcalls: Stop improperly reporting fp128 long double calls on ARM (PR #215917)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Will all these impls eventually be getting some form of asm fallback?

Not sure what you mean. An implementation needs to exist somewhere, someone has to put in the work to implement it somewhere the toolchain knows will be linked 

https://github.com/llvm/llvm-project/pull/215917