fix clang compilation

src/camr.cc

@@ -544,9 +544,6 @@ bool CAmr::checkGravity(const int ngrida, const int ilevel, const int icpu, int
   assert(nvarg==ndim);
   assert(ngrida>0);
 
-  // pointer to gridfile
-  int (*pgf)[nlevelmax][ncpu+nboundary] = (int (*)[nlevelmax][ncpu+nboundary]) gridfile;
-
   //double * varg = new double[ngrida*twotondim]; // allocate temporary variable
   int sdouble = sizeof(double); // sizeof double
 
@@ -555,7 +552,7 @@ bool CAmr::checkGravity(const int ngrida, const int ilevel, const int icpu, int
   try {
     for (int j=0; j<(nboundary+ncpu); j++) {
       grav.skipBlock(2);
-      if ((*pgf)[ilevel][j]>0) {
+      if (gridfile[ilevel*(ncpu+nboundary)+j]>0) {
         // Read grav variables
         for (int ind=0;ind<twotondim;ind++) {
           for (int ivar=0; ivar<nvarg; ivar++) {