Added stub for SetThreadExecutionState (new function in Win98/2000).

diff --git a/include/winbase.h b/include/winbase.h
index 661f86c..9b8ac1c 100644
--- a/include/winbase.h
+++ b/include/winbase.h
@@ -1570,6 +1570,7 @@
 DWORD       WINAPI SetTapePosition(HANDLE,DWORD,DWORD,DWORD,DWORD,BOOL);
 DWORD       WINAPI SetThreadAffinityMask(HANDLE,DWORD);
 BOOL        WINAPI SetThreadContext(HANDLE,const CONTEXT *);
+DWORD       WINAPI SetThreadExecutionState(EXECUTION_STATE);
 BOOL        WINAPI SetThreadLocale(LCID);
 BOOL        WINAPI SetThreadPriority(HANDLE,INT);
 BOOL        WINAPI SetThreadPriorityBoost(HANDLE,BOOL);