[WebAssembly] Implement mixed-type ISD::FCOPYSIGN.

ISD::FCOPYSIGN permits its operands to have differing types, and DAGCombiner
uses this. Add some def : Pat rules to expand this out into an explicit
conversion and a normal copysign operation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255220 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed