fix assert to check instead of assign

Author: svigerske

src/ClpSolver.cpp

@@ -4292,7 +4292,7 @@ static void statistics(ClpSimplex * originalModel, ClpSimplex * model) {
                     }
                   } else {
                     int row2 = mapRow[iRow];
-                    assert(iRow = mapRow[row2]);
+                    assert(iRow == mapRow[row2]);
                     if (rowLower[iRow] != rowLower[row2] ||
                         rowLower[row2] != rowLower[iRow])
                       good = false;