ReportsBase.cc: Dereference after null check error spotted by Coverity

Original author: rlong

CID 1503710: Dereference after null check in WriteAnnotatedReport().

   12. var_compare_op: Comparing info.uncoveredRanges to null implies that info.uncoveredRanges might be null.
   13. Condition info.uncoveredBranches == NULL, taking false branch.
219    if ((info.uncoveredRanges == NULL) &&
220        (info.uncoveredBranches == NULL))
   5. Continuing loop.
   9. Continuing loop.
221      continue;
222
223    // If uncoveredRanges and uncoveredBranches are empty, then everything
224    // must have been covered for this symbol.  Just skip it.
   CID 1503710 (#1 of 1): Dereference after null check (FORWARD_NULL)14. var_deref_model: Passing null pointer info.uncoveredRanges->set to empty, which dereferences it. [show details]
225    if ((info.uncoveredRanges->set.empty()) &&
226        (info.uncoveredBranches->set.empty()))
227      continue;