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

The patch is generated using this command:

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


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 93e34d1..05bb019 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -6604,7 +6604,7 @@
       MachineFunctionPass::getAnalysisUsage(AU);
     }
   };
-}
+} // namespace
 
 char CGBR::ID = 0;
 FunctionPass*
@@ -6716,7 +6716,7 @@
       MachineFunctionPass::getAnalysisUsage(AU);
     }
   };
-}
+} // namespace
 
 char LDTLSCleanup::ID = 0;
 FunctionPass*