UseJava: add INCLUDE_MODULES argument to add_jar

Arguments are added to the dependencies list, and to the "--module-path"
passed to javac, which is only generated for adequate JDK versions.

Tests/JavaModExportImport/Import/Import.java

@@ -0,0 +1,13 @@
+import org.foo.Foo;
+import com.bar.Bar;
+
+class Import
+{
+  public static void main(String args[])
+  {
+    Foo foo = new Foo();
+    Bar bar = new Bar();
+    foo.printName();
+    bar.printName();
+  }
+}