ENH: use .exe on vms

Modules/Platform/OpenVMS.cmake

@@ -5,3 +5,4 @@ SET(CMAKE_C_CREATE_STATIC_LIBRARY
   "<CMAKE_RANLIB> <TARGET>"
   )
 SET(CMAKE_CXX_CREATE_STATIC_LIBRARY ${CMAKE_C_CREATE_STATIC_LIBRARY})
+SET(CMAKE_EXECUTABLE_SUFFIX ".exe")          # .exe

Source/kwsys/SystemTools.cxx

@@ -431,7 +431,7 @@ bool SystemTools::PutEnv(const char* value)
 
 const char* SystemTools::GetExecutableExtension()
 {
-#if defined(_WIN32) || defined(__CYGWIN__)
+#if defined(_WIN32) || defined(__CYGWIN__) || defined(__VMS)
   return ".exe";
 #else
   return "";