Add missing const specifiers.

src/yaxt_f2c.c

@@ -492,7 +492,7 @@ PPM_DSO_INTERNAL void *
 xt_redist_single_array_base_custom_new_c2f(
   int nsend, int nrecv, const struct xt_redist_msg_f *send_msgs_f,
   const struct xt_redist_msg_f *recv_msgs_f, MPI_Fint comm_f,
-  struct xt_config_f *config);
+  const struct xt_config_f *config);
 
 PPM_DSO_INTERNAL void *
 xt_redist_single_array_base_new_c2f(int nsend, int nrecv,
@@ -509,7 +509,7 @@ PPM_DSO_INTERNAL void *
 xt_redist_single_array_base_custom_new_c2f(
   int nsend, int nrecv, const struct xt_redist_msg_f *send_msgs_f,
   const struct xt_redist_msg_f *recv_msgs_f, MPI_Fint comm_f,
-  struct xt_config_f *config)
+  const struct xt_config_f *config)
 {
   assert(nsend >= 0 && nrecv >= 0);
   MPI_Comm comm_c = MPI_Comm_f2c(comm_f);