[clang-format] Fix FixNamespaceComments when BraceWrapping AfterNamespace is true.
Summary:
NamespaceEndCommentsFixer did not fix namespace comments when the brace opening the namespace was not on the same line as the "namespace" keyword.
It occurs in Allman, GNU and Linux styles and whenever BraceWrapping.AfterNamespace is true.
Before:
```lang=cpp
namespace a
{
void f();
void g();
}
```
After:
```lang=cpp
namespace a
{
void f();
void g();
} // namespace a
```
Reviewers: krasimir
Reviewed By: krasimir
Subscribers: klimek, cfe-commits
Differential Revision: https://reviews.llvm.org/D37904
llvm-svn: 314279