Add an opal_attribute_unused in here since we're no longer using this

parameter (I just discovered while researching for v1.4 that v1.4 has
effectively this same function definition: it just always returns
true!).

This commit was SVN r22642.

ompi/datatype/ompi_datatype.h

@@ -136,7 +136,7 @@ ompi_datatype_is_overlapped( const ompi_datatype_t* type )
 }
 
 static inline int32_t
-ompi_datatype_is_acceptable_for_one_sided( const ompi_datatype_t* type )
+ompi_datatype_is_acceptable_for_one_sided( const ompi_datatype_t* type __opal_attribute_unused__ )
 {
     /* Please see https://svn.open-mpi.org/trac/ompi/ticket/2233.