[KLIB] Add regression test

compiler/testData/codegen/box/ir/serializationRegressions/signatureClash.kt

@@ -0,0 +1,26 @@
+// IGNORE_BACKEND: JS
+// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JVM_IR
+// IGNORE_BACKEND: NATIVE
+// IGNORE_BACKEND_FIR: JVM_IR
+// MODULE: lib
+// FILE: lib.kt
+
+open class Base<T> {
+    open fun foo(p1: T): String { return "p1:$p1" }
+    open fun foo(p2: String): String { return "p2:$p2" }
+}
+class Derived : Base<String>()
+
+
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+fun box(): String {
+    val d = Derived()
+    if (d.foo(p1 = "42") != "p1:42") return "FAIL1"
+    if (d.foo(p2 = "24") != "p2:24") return "FAIL2"
+
+    return "OK"
+}