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

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1908,7 +1908,7 @@ namespace {
     
     llvm::APInt getAsInteger() const;
   };
-}
+} // namespace
 
 void ModuleSignature::add(uint64_t Value, unsigned int NumBits) {
   CurValue |= Value << CurBit;