Implements brace breaking styles.

We now support "Linux" and "Stroustrup" brace breaking styles, which
gets us one step closer to support formatting WebKit, KDE & Linux code.

Linux brace breaking style:
namespace a
{
class A
{
  void f()
  {
    if (x) {
      f();
    } else {
      g();
    }
  }
}
}

Stroustrup brace breaking style:
namespace a {
class A {
  void f()
  {
    if (x) {
      f();
    } else {
      g();
    }
  }
}
}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181700 91177308-0d34-0410-b5e6-96231b3b80d8