Normalize the include guard style.

An leading underscore followed by a capital letter is a reserved
name space in C and C++.

This change also moves any #include directives within the include
guard in some of the compiler/codegen/arm header files.

Change-Id: I9715e2c5301699d31886e61d0fe6e29483555a2a
diff --git a/libdex/DexDataMap.h b/libdex/DexDataMap.h
index 359d3ad..7e43dc9 100644
--- a/libdex/DexDataMap.h
+++ b/libdex/DexDataMap.h
@@ -18,8 +18,8 @@
  * Verification-time map of data section items
  */
 
-#ifndef _LIBDEX_DEXDATAMAP
-#define _LIBDEX_DEXDATAMAP
+#ifndef LIBDEX_DEXDATAMAP_H_
+#define LIBDEX_DEXDATAMAP_H_
 
 #include "DexFile.h"
 
@@ -70,4 +70,4 @@
     return dexDataMapVerify(map, offset, type);
 }
 
-#endif /*_LIBDEX_DEXDATAMAP*/
+#endif  // LIBDEX_DEXDATAMAP_H_