Fixed the only -Wsometimes-uninitialized warning

Moved the logging into the `if`, which I think is what the author probably intended.

c++/examples/h5tutr_extend.cpp

@@ -99,7 +99,7 @@ main(void)
         // ---------------------------------------
 
         int     rdata[10][3];
-        int     i, j, rank, rank_chunk;
+        int     i, j, rank;
         hsize_t chunk_dimsr[2], dimsr[2];
 
         // Open the file and dataset.
@@ -114,10 +114,10 @@ main(void)
         rank            = filespace->getSimpleExtentNdims();
         (void)filespace->getSimpleExtentDims(dimsr);
 
-        if (H5D_CHUNKED == prop.getLayout())
-            rank_chunk = prop.getChunk(rank, chunk_dimsr);
-        cout << "rank chunk = " << rank_chunk << endl;
-        ;
+        if (H5D_CHUNKED == prop.getLayout()) {
+            int rank_chunk = prop.getChunk(rank, chunk_dimsr);
+            cout << "rank chunk = " << rank_chunk << endl;
+        }
 
         memspace = new DataSpace(rank, dimsr, NULL);
         dataset->read(rdata, PredType::NATIVE_INT, *memspace, *filespace);