JVM_IR KT-50856 fix generic signature for SAM proxy function

compiler/testData/codegen/box/invokedynamic/sam/functionRefToJavaInterface/kt50856.kt

@@ -0,0 +1,24 @@
+// TARGET_BACKEND: JVM_IR
+// JVM_TARGET: 1.8
+// WITH_STDLIB
+// FILE: box.kt
+fun <U> get(x: Sam<U>): U =
+    x.get()
+
+fun test() {
+    get<Map<String, String>>(::mutableMapOf)
+}
+
+fun box(): String {
+    test()
+    return "OK"
+}
+
+// FILE: Sam.java
+public interface Sam<T> {
+    T get();
+
+    static void run() {
+        BoxKt.test();
+    }
+}