Build stubs for modifiers

idea/testData/decompiler/decompiledTextJvm/Modifiers.expected.kt

@@ -0,0 +1,11 @@
+// IntelliJ API Decompiler stub source generated from a class file
+// Implementation of methods is not available
+
+package test
+
+public final class Modifiers public constructor() {
+    public final var extVar: kotlin.Int /* compiled code */
+
+    public final external fun extFun(): kotlin.Unit { /* compiled code */ }
+}
+