/*D
   MPI_Comm_free_keyval - Frees an attribute key for communicators

Synopsis:
.vb
int MPI_Comm_free_keyval(int *comm_keyval)
.ve

Input/Output Parameters:
. comm_keyval - key value (integer)

.N ThreadSafe

.N Fortran

.N Errors
.N MPI_SUCCESS
.N MPI_ERR_KEYVAL
.N MPI_ERR_OTHER

D*/

