disable/enable msvc headers are allowed to be included multiple times

Eigen/src/Core/util/DisableMSVCWarnings.h

diff --git a/Eigen/src/Core/util/DisableMSVCWarnings.h b/Eigen/src/Core/util/DisableMSVCWarnings.h
index 2626c24..1f3592b 100644
--- a/Eigen/src/Core/util/DisableMSVCWarnings.h
+++ b/Eigen/src/Core/util/DisableMSVCWarnings.h
@@ -1,9 +1,5 @@
-#ifndef EIGEN_DISABLEMSVCWARNINGS_H
-#define EIGEN_DISABLEMSVCWARNINGS_H
 
 #ifdef _MSC_VER
   #pragma warning( push )
   #pragma warning( disable : 4181 4244 4127 4211 )
 #endif
-
-#endif // EIGEN_DISABLEMSVCWARNINGS_H

Eigen/src/Core/util/EnableMSVCWarnings.h

diff --git a/Eigen/src/Core/util/EnableMSVCWarnings.h b/Eigen/src/Core/util/EnableMSVCWarnings.h
index 23905c1..8bd6160 100644
--- a/Eigen/src/Core/util/EnableMSVCWarnings.h
+++ b/Eigen/src/Core/util/EnableMSVCWarnings.h
@@ -1,9 +1,4 @@
-#ifndef EIGEN_ENABLEMSVCWARNINGS_H
-#define EIGEN_ENABLEMSVCWARNINGS_H
 
 #ifdef _MSC_VER
   #pragma warning( pop )
 #endif
-
-#endif // EIGEN_ENABLEMSVCWARNINGS_H
-