Change fallthrough comment so it is also recognized by newer GCC versions.

src/pio_roles.c

@@ -109,7 +109,7 @@ cdiPioCSRBalanced(MPI_Comm commSuper, int IOMode, int nProcsIO)
   case PIO_ASYNCH:
     specialRole = PIO_ROLE_WRITER;
     collType = PIO_ROLE_COLLECTOR;
-    /* fallthrough intentional */
+    /*-fallthrough*/
   case PIO_FPGUARD:
     clientsPerCollectorMin = numClients / (nProcsIO - 1);
     rest = numClients % nProcsIO;