Do not rely on descriptors in KParameterImpl.equals/hashCode

For the same reason as in the previous commit: descriptors are cached
via weak references in moduleByClassLoader.kt and can be
garbage-collected at any point. So different instances of KParameterImpl
representing the same parameter may store different instances of
descriptors.

compiler/testData/codegen/box/reflection/methodsFromAny/parametersEqualsWithClearCaches.kt

@@ -0,0 +1,46 @@
+// TARGET_BACKEND: JVM
+// WITH_REFLECT
+// FILE: box.kt
+
+import kotlin.reflect.KMutableProperty
+import kotlin.test.assertEquals
+
+inline fun check(message: String, generate: () -> Any?) {
+    val x1: Any?
+    val x2: Any?
+    try {
+        x1 = generate()
+
+        // Force clear the internal maps, as if the weak values in them are garbage-collected.
+        kotlin.reflect.jvm.internal.ReflectionFactoryImpl.clearCaches()
+
+        x2 = generate()
+    } catch (e: Throwable) {
+        throw AssertionError("Fail $message", e)
+    }
+
+    assertEquals(x1, x2, "Fail equals $message")
+    assertEquals(x2, x1, "Fail equals $message")
+    assertEquals(x1.hashCode(), x2.hashCode(), "Fail hashCode $message")
+}
+
+class C(c: Any) {
+    fun Any.a(a: Any): Any = a
+
+    var <X> X.x: X
+        get() = this
+        set(value) {}
+}
+
+fun box(): String {
+    check("constructor parameter") { C::class.constructors.single().parameters.single() }
+    check("instance parameter") { C::class.members.single { it.name == "a" }.parameters[0] }
+    check("value parameter") { C::class.members.single { it.name == "a" }.parameters[1] }
+
+    check("extension receiver parameter") { (C::class.members.single { it.name == "x" } as KMutableProperty<*>).parameters[1] }
+
+    // TODO: depends on KT-13490
+    // check("property setter parameter") { (C::class.members.single { it.name == "x" } as KMutableProperty<*>).setter.parameters[2] }
+
+    return "OK"
+}