[KLIB] Add regression to about VarAsFun type parameter leak

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

@@ -0,0 +1,15 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// MODULE: lib
+// FILE: l1.kt
+
+val <T : CharSequence> T.z
+    get() = { x: T -> this }
+
+// FILE: l2.kt
+
+fun test(ok: String, fail: String) = ok.z(fail)
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+fun box() = test("OK", "FAIL")