use NC_CLASSIC_MODEL to remove dependence on hdf5

Author: chengcli

src/outputs/mppnccombine.cpp

@@ -192,7 +192,7 @@ int mppnccombine(int argc, char *argv[]) {
       free(ncoutfile);
       return (1);
     }
-    if ((ncoutfile->ncfid = nccreate(outfilename, NC_NETCDF4)) == (-1)) {
+    if ((ncoutfile->ncfid = nccreate(outfilename, NC_CLASSIC_MODEL)) == (-1)) {
       fprintf(stderr, "Error: cannot create the output netCDF file!\n");
       free(ncoutfile);
       return (1);

src/outputs/netcdf.cpp

@@ -105,7 +105,7 @@ void NetcdfOutput::WriteOutputFile(Mesh *pm, ParameterInput *pin, bool flag) {
     std::stringstream msg;
     int ifile;
 
-    nc_create(fname.c_str(), NC_NETCDF4, &ifile);
+    nc_create(fname.c_str(), NC_CLASSIC_MODEL, &ifile);
 
     // 2. coordinate structure
     int ncells1 = out_ie - out_is + 1;