Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)

Apparently, the style needs to be agreed upon first.

llvm-svn: 240390
diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index 0bb0fa3..530ab46 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -55,7 +55,7 @@
     bool isIdempotentRMW(AtomicRMWInst *AI);
     bool simplifyIdempotentRMW(AtomicRMWInst *AI);
   };
-} // namespace
+}
 
 char AtomicExpand::ID = 0;
 char &llvm::AtomicExpandID = AtomicExpand::ID;