SIP-23 Account for literal types in varargs translation

Top level modules in Scala currently desugar as:

```
class C; object O extends C { toString }
```

```
public final class O$ extends C {
  public static final O$ MODULE$;

  public static {};
    Code:
       0: new           #2                  // class O$
       3: invokespecial #12                 // Method "<init>":()V
       6: return

  private O$();
    Code:
       0: aload_0
       1: invokespecial #13                 // Method C."<init>":()V
       4: aload_0
       5: putstatic     #15                 // Field MODULE$:LO$;
       8: aload_0
       9: invokevirtual #21                 // Method java/lang/Object.toString:()Ljava/lang/String;
      12: pop
      13: return
}
```

The static initalizer `<clinit>` calls the constructor `<init>`, which
invokes superclass constructor, assigns `MODULE$= this`, and then runs
the remainder of the object's constructor (`toString` in the example
above.)

It turns out that this relies on a bug in the JVM's verifier: assignment to a
static final must occur lexically within the <clinit>, not from within `<init>`
(even if the latter is happens to be called by the former).

I'd like to move the assignment to <clinit> but that would
change behaviour of "benign" cyclic references between modules.

Example:

```
package p1; class CC { def foo = O.bar}; object O {new CC().foo; def bar = println(1)};

// Exiting paste mode, now interpreting.

scala> p1.O
1
```

This relies on the way that we assign MODULE$ field after the super class constructors
are finished, but before the rest of the module constructor is called.

Instead, this commit removes the ACC_FINAL bit from the field. It actually wasn't
behaving as final at all, precisely the issue that the stricter verifier
now alerts us to.

```
scala> :paste -raw
// Entering paste mode (ctrl-D to finish)

package p1; object O

// Exiting paste mode, now interpreting.

scala> val O1 = p1.O
O1: p1.O.type = p1.O$@ee7d9f1

scala> scala.reflect.ensureAccessible(p1.O.getClass.getDeclaredConstructor()).newInstance()
res0: p1.O.type = p1.O$@64cee07

scala> O1 eq p1.O
res1: Boolean = false
```

We will still achieve safe publication of the assignment to other threads
by virtue of the fact that `<clinit>` is executed within the scope of
an initlization lock, as specified by:

  https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-5.html#jvms-5.5

Fixes scala/scala-dev#SD-194

Non local returns aren't eliminated after inlined in 2.11 or 2.12

```
⚡ scala
Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_112).
Type in expressions for evaluation. Or try :help.

scala> @inlune def foo(a: => Any) = if ("".isEmpty) a else ""
<console>:11: error: not found: type inlune
       @inlune def foo(a: => Any) = if ("".isEmpty) a else ""
        ^

scala> @inline def foo(a: => Any) = if ("".isEmpty) a else ""
foo: (a: => Any)Any

scala> class InlineReturn { def test: Any = foo(return "") }
defined class InlineReturn

scala> :javap -c InlineReturn#test
  public java.lang.Object test();
    Code:
       0: new           #4                  // class java/lang/Object
       3: dup
       4: invokespecial scala#32                 // Method java/lang/Object."<init>":()V
       7: astore_1
       8: getstatic     scala#36                 // Field $line4/$read$$iw$$iw$.MODULE$:L$line4/$read$$iw$$iw$;
      11: aload_1
      12: invokedynamic scala#59,  0             // InvokeDynamic #0:apply:(Ljava/lang/Object;)Lscala/Function0;
      17: invokevirtual scala#63                 // Method $line4/$read$$iw$$iw$.foo:(Lscala/Function0;)Ljava/lang/Object;
      20: goto          44
      23: astore_2
      24: aload_2
      25: invokevirtual scala#66                 // Method scala/runtime/NonLocalReturnControl.key:()Ljava/lang/Object;
      28: aload_1
      29: if_acmpne     39
      32: aload_2
      33: invokevirtual scala#69                 // Method scala/runtime/NonLocalReturnControl.value:()Ljava/lang/Object;
      36: goto          41
      39: aload_2
      40: athrow
      41: goto          44
      44: areturn
    Exception table:
       from    to  target type
           8    20    23   Class scala/runtime/NonLocalReturnControl
```

```
⚡ ~/scala/2.11.8/bin/scala
Welcome to Scala 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_112).
Type in expressions for evaluation. Or try :help.

scala> @inline def foo(a: => Any) = if ("".isEmpty) a else ""
foo: (a: => Any)Any

scala> class InlineReturn { def test: Any = foo(return "") }
defined class InlineReturn

scala> :javap -c InlineReturn#test
  public java.lang.Object test();
    Code:
       0: new           #4                  // class java/lang/Object
       3: dup
       4: invokespecial #13                 // Method java/lang/Object."<init>":()V
       7: astore_1
       8: getstatic     #19                 // Field .MODULE$:L;
      11: new           #21                 // class InlineReturn$$anonfun$test$1
      14: dup
      15: aload_0
      16: aload_1
      17: invokespecial #24                 // Method InlineReturn$$anonfun$test$1."<init>":(LInlineReturn;Ljava/lang/Object;)V
      20: invokevirtual scala#28                 // Method .foo:(Lscala/Function0;)Ljava/lang/Object;
      23: goto          39
      26: astore_2
      27: aload_2
      28: invokevirtual scala#31                 // Method scala/runtime/NonLocalReturnControl.key:()Ljava/lang/Object;
      31: aload_1
      32: if_acmpne     40
      35: aload_2
      36: invokevirtual scala#34                 // Method scala/runtime/NonLocalReturnControl.value:()Ljava/lang/Object;
      39: areturn
      40: aload_2
      41: athrow
    Exception table:
       from    to  target type
           8    26    26   Class scala/runtime/NonLocalReturnControl

scala> :quit
```