mapi32: Remove redundant protections against duplicate header inclusion.

include/mapidefs.h

diff --git a/include/mapidefs.h b/include/mapidefs.h
index 219177d..b753045 100644
--- a/include/mapidefs.h
+++ b/include/mapidefs.h
@@ -24,9 +24,7 @@
 #endif
 
 #include <winerror.h>
-#ifndef _OBJBASE_H_
 #include <objbase.h>
-#endif
 #include <stddef.h>
 
 /* Some types from other headers */

include/mapix.h

diff --git a/include/mapix.h b/include/mapix.h
index e511cdf..1ca7aaf 100644
--- a/include/mapix.h
+++ b/include/mapix.h
@@ -19,18 +19,10 @@
 #ifndef MAPIX_H
 #define MAPIX_H
 
-#ifndef MAPIDEFS_H
 #include <mapidefs.h>
-#endif
-#ifndef MAPICODE_H
 #include <mapicode.h>
-#endif
-#ifndef MAPIGUID_H
 #include <mapiguid.h>
-#endif
-#ifndef MAPITAGS_H
 #include <mapitags.h>
-#endif
 
 #ifdef __cplusplus
 extern "C" {