Fixed/added namespace ending comments using clang-tidy. NFC

The patch is generated using this command:

  $ tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
      -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
      work/llvm/tools/clang

To reduce churn, not touching namespaces spanning less than 10 lines.

llvm-svn: 240270
diff --git a/clang/lib/AST/NestedNameSpecifier.cpp b/clang/lib/AST/NestedNameSpecifier.cpp
index 50a0050..0592621 100644
--- a/clang/lib/AST/NestedNameSpecifier.cpp
+++ b/clang/lib/AST/NestedNameSpecifier.cpp
@@ -377,7 +377,7 @@
     memcpy(&Result, static_cast<char *>(Data) + Offset, sizeof(void*));
     return Result;
   }
-}
+} // namespace
 
 SourceRange NestedNameSpecifierLoc::getSourceRange() const {
   if (!Qualifier)
@@ -470,7 +470,7 @@
            reinterpret_cast<char *>(&Ptr) + sizeof(void *),
            Buffer, BufferSize, BufferCapacity);
   }
-}
+} // namespace
 
 NestedNameSpecifierLocBuilder::
 NestedNameSpecifierLocBuilder(const NestedNameSpecifierLocBuilder &Other)