Always treat all sources as parts of the module being compiled

If a path to the module-info.java file is passed as an argument, we
should treat all other source files passed as arguments (either as
individual source files or inside a source directory) as members of that
module. Previously we treated other source files as members of the
unnamed module, and this resulted in incorrect errors when using a
member exported with a qualification from another named module, for
example

 #KT-18598 In Fixed

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/modules/JavaModule.kt

@@ -28,8 +28,9 @@ interface JavaModule {
     val name: String
 
     /**
-     * A directory or the root of a .jar file on the module path. In case of an explicit module,
-     * module-info.class file can be found in its children.
+     * A directory or the root of a .jar file on the module path. Can also be the path to the `module-info.java` file if that path
+     * was passed as an explicit argument to the compiler.
+     * In case of an explicit module, module-info.class file can be found in its children.
      */
     val moduleRoot: VirtualFile