Add missing const specifier.

src/pio_server.c

@@ -171,7 +171,8 @@ setupClientRanks(void)
 }
 
 static void
-createClientStreamBuf(size_t streamIdx, struct clientBufSize *bufSizes,
+createClientStreamBuf(size_t streamIdx,
+                      const struct clientBufSize *bufSizes,
                       const struct cdiPioConf *conf)
 {
   size_t streamBufferSize = 0;