The wasm backend fetches the tan runtime lib call in
`llvm/include/llvm/IR/RuntimeLibcalls.def` via `StaticLibcallNameMap()`,
but ignores the runtime function because a function sinature mapping is
not specified in RuntimeLibcallSignatureTable(). The fix is to specify
the function signatures for float32-128.
This is a fix for a build break reported on PR
https://github.com/llvm/llvm-project/pull/94559#issuecomment-2159923215.
38ccee0034