Fix signature of accessor for suspend function

It must be a suspend function too to have an additional Continuation parameter

 #KT-15715 Fixed

compiler/testData/codegen/box/coroutines/accessorForSuspend.kt

@@ -0,0 +1,34 @@
+// WITH_RUNTIME
+// WITH_COROUTINES
+import kotlin.coroutines.*
+import kotlin.coroutines.intrinsics.*
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(EmptyContinuation)
+}
+
+class A {
+    suspend private fun a(): String = suspendCoroutineOrReturn { x ->
+        x.resume("OK")
+        SUSPENDED_MARKER
+    }
+
+    suspend fun myfun(): String {
+        var result = "fail"
+        builder {
+            result = a()
+        }
+
+        return result
+    }
+}
+
+fun box(): String {
+    var result = ""
+
+    builder {
+        result = A().myfun()
+    }
+
+    return result
+}