- Move from using include guards to pragma once.

- Whilst this is non-standard and potentially makes the code less portable, it's supported by both gcc and msvc and should bringg increased compilation speed due to its optimized behaviour (doesn't need to invoke the preprocessor)
- Patch by Amine Khaldi [amine.khaldi@reactos.org]

svn path=/trunk/; revision=45685

reactos/base/applications/taskmgr/perfdata.h

@@ -20,8 +20,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#ifndef __PERFDATA_H
-#define __PERFDATA_H
+#pragma once
 
 #ifdef __cplusplus
 extern "C" {
@@ -106,5 +105,3 @@ ULONG	PerfDataGetTotalThreadCount(void);
 #ifdef __cplusplus
 };
 #endif
-
-#endif /* __PERFDATA_H */