Added missing ifdef

src/molfile/crdplugin.cpp

@@ -34,6 +34,7 @@ OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 
 OTHER DEALINGS WITH THE SOFTWARE.
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
+#ifdef __PLUMED_INTERNAL_MOLFILE_PLUGINS
 /***************************************************************************
  *cr
  *cr            (C) Copyright 1995-2009 The Board of Trustees of the
@@ -257,3 +258,5 @@ VMDPLUGIN_API int VMDPLUGIN_fini(void) { return VMDPLUGIN_SUCCESS; }
 }
 }
 
+#endif
+