Fix NPE in KCallable.isAccessible for interfaces loaded by boot class loader

Class.getClassLoader returns null for classes loaded by the system class
loader (the one used to start the application). In this case we need to
use ClassLoader.getSystemClassLoader. We already have an extension
`safeClassLoader` specifically for this purpose in reflection.jvm, but
forgot to use it in d59f2bcc80.

 #KT-37707 Fixed

compiler/testData/codegen/box/reflection/functions/isAccessibleOnAllMembers.kt

@@ -0,0 +1,20 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_FIR: JVM_IR
+// WITH_REFLECT
+
+import kotlin.reflect.jvm.isAccessible
+
+fun box(): String {
+    val members = Observer::class.members
+    for (member in members) {
+        member.isAccessible = true
+    }
+    return members.single { it.name == "result" }.call(Observer()) as String
+}
+
+class Observer : AutoCloseable {
+    override fun close() {
+    }
+
+    private fun result() = "OK"
+}