Canonicalize header guards into a common format.

Add header guards to files that were missing guards. Remove #endif comments
as they don't seem common in LLVM (we can easily add them back if we decide
they're useful)

Changes made by clang-tidy with minor tweaks.

llvm-svn: 215558
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.h b/llvm/lib/Bitcode/Reader/BitcodeReader.h
index 0b3c1c1..5bbcaf4 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.h
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef BITCODE_READER_H
-#define BITCODE_READER_H
+#ifndef LLVM_LIB_BITCODE_READER_BITCODEREADER_H
+#define LLVM_LIB_BITCODE_READER_BITCODEREADER_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/Bitcode/BitstreamReader.h"
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.h b/llvm/lib/Bitcode/Writer/ValueEnumerator.h
index 6248893..eba768d 100644
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.h
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef VALUE_ENUMERATOR_H
-#define VALUE_ENUMERATOR_H
+#ifndef LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H
+#define LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"