Fix type casting in stencil test

hpvm/test/parboil/benchmarks/stencil/src/visc/stencil.cpp

@@ -219,9 +219,9 @@ int main(int argc, char** argv) {
 
 
     //only use 1D thread block
-    int tx =256;
-    long block[3] = {tx,1,1};
-    long grid[3] = {(nx-2+tx-1)/tx*tx,ny-2,nz-2};
+    size_t tx = 256;
+    size_t block[3] = {tx,1,1};
+    size_t grid[3] = {((unsigned)nx-2+tx-1)/tx*tx,(unsigned)ny-2,(unsigned)nz-2};
     //size_t grid[3] = {nx-2,ny-2,nz-2};
     size_t offset[3] = {1,1,1};