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/Transforms/Instrumentation/DebugIR.h b/llvm/lib/Transforms/Instrumentation/DebugIR.h
index 02831ed..8d74a4d 100644
--- a/llvm/lib/Transforms/Instrumentation/DebugIR.h
+++ b/llvm/lib/Transforms/Instrumentation/DebugIR.h
@@ -13,8 +13,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_TRANSFORMS_INSTRUMENTATION_DEBUGIR_H
-#define LLVM_TRANSFORMS_INSTRUMENTATION_DEBUGIR_H
+#ifndef LLVM_LIB_TRANSFORMS_INSTRUMENTATION_DEBUGIR_H
+#define LLVM_LIB_TRANSFORMS_INSTRUMENTATION_DEBUGIR_H
 
 #include "llvm/Pass.h"
 
@@ -95,4 +95,4 @@
 
 } // llvm namespace
 
-#endif // LLVM_TRANSFORMS_INSTRUMENTATION_DEBUGIR_H
+#endif