[Native] Support multiple suspend lambdas as class supertypes

Drop the backend check. Eveything else is already fixed in
https://github.com/JetBrains/kotlin/commit/3b3318ab06e8c55b1c49da5734decd59524c3d9f

^KT-46775

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/SpecialBackendChecksTraversal.kt

@@ -21,7 +21,6 @@ import org.jetbrains.kotlin.backend.konan.ir.companionObject
 import org.jetbrains.kotlin.backend.konan.ir.getSuperClassNotAny
 import org.jetbrains.kotlin.backend.konan.llvm.IntrinsicType
 import org.jetbrains.kotlin.backend.konan.llvm.tryGetIntrinsicType
-import org.jetbrains.kotlin.builtins.functions.FunctionClassKind
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
@@ -29,7 +28,6 @@ import org.jetbrains.kotlin.descriptors.isFinalClass
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
-import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
@@ -593,41 +591,9 @@ private class BackendChecker(val context: Context, val irFile: IrFile) : IrEleme
         if (declaration.isKotlinObjCClass()) {
             checkKotlinObjCClass(declaration)
         }
-        checkNotImplementsMultipleSuspendLambdas(declaration)
     }
 }
 
-// TODO: remove this check in KT-46775
-private fun BackendChecker.checkNotImplementsMultipleSuspendLambdas(clazz: IrClass) {
-    var suspendFunctionClassSymbol: IrClassSymbol? = null // Can be null (no suspend function supertypes) or non-null (the single one).
-
-    fun checkSupertype(superType: IrType): Boolean {
-        val superTypeClassSymbol = superType.classOrNull
-                ?: return true // This is not a class. Continue with others.
-
-        return when {
-            superTypeClassSymbol.isFunctionMarker() -> true // Continue with others.
-            superTypeClassSymbol.isFunction() -> {
-                // Mixing suspend and non-suspend function supertypes is not allowed by the frontend. So can stop here.
-                false
-            }
-            superTypeClassSymbol.isSuspendFunction() -> {
-                suspendFunctionClassSymbol = when (suspendFunctionClassSymbol) {
-                    null, superTypeClassSymbol -> superTypeClassSymbol
-                    else -> reportError(clazz, "Multiple suspend function types as supertypes are not supported yet")
-                }
-                true // Continue with others.
-            }
-            else -> {
-                // Recurse with supertypes.
-                superTypeClassSymbol.owner.superTypes.all(::checkSupertype)
-            }
-        }
-    }
-
-    clazz.superTypes.all(::checkSupertype)
-}
-
 private fun BackendChecker.checkCanGenerateCCall(expression: IrCall, isInvoke: Boolean) {
     val callee = expression.symbol.owner