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/Target/NVPTX/NVPTXMachineFunctionInfo.h b/llvm/lib/Target/NVPTX/NVPTXMachineFunctionInfo.h
index 67fb390..10f1135 100644
--- a/llvm/lib/Target/NVPTX/NVPTXMachineFunctionInfo.h
+++ b/llvm/lib/Target/NVPTX/NVPTXMachineFunctionInfo.h
@@ -12,6 +12,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifndef LLVM_LIB_TARGET_NVPTX_NVPTXMACHINEFUNCTIONINFO_H
+#define LLVM_LIB_TARGET_NVPTX_NVPTXMACHINEFUNCTIONINFO_H
+
 #include "llvm/CodeGen/MachineFunction.h"
 
 namespace llvm {
@@ -44,3 +47,5 @@
   }
 };
 }
+
+#endif