16.2.12: Clarify DU/DA analysis for loop containing break

JLS 16.2.11 has a problem with ForUpdate statements. The
following program gives a compile-time error with javac:

class C {
  void bar() {
    for (final int i; 0 < (i = 1); i = i + 1)
      break;
  }
}

Yet the current wording in the JLS permits it as legal. i is DU after
the init part, i is both DA and DU after the contained break, and there
are no continue statements; therefore i is DU before the condition
expression (16.2.11.d) and may be assigned there. Further, since i is
both DA and DU after the contained break, and there are no continue
statements, the increment statement is not violating either rule that a
variable must be DA before access or DU before assignment. Compare this
to a program with similar semantics, which does compile:

class D {
  void bar() {
    final int i;
  label:
    if (0 < (i = 1)) {
      if (true)
        break label;
      i = i + 1;
    }
  }
}