backport: checks and fixes from static code analyzers results

original commit: 71f665bd8c

modules/flann/include/opencv2/flann/result_set.h

@@ -160,7 +160,8 @@ class KNNResultSet : public ResultSet<DistanceType>
     DistanceType worst_distance_;
 
 public:
-    KNNResultSet(int capacity_) : capacity(capacity_), count(0)
+    KNNResultSet(int capacity_)
+        : indices(NULL), dists(NULL), capacity(capacity_), count(0), worst_distance_(0)
     {
     }
 
@@ -186,6 +187,8 @@ public:
 
     void addPoint(DistanceType dist, int index) CV_OVERRIDE
     {
+        CV_DbgAssert(indices);
+        CV_DbgAssert(dists);
         if (dist >= worst_distance_) return;
         int i;
         for (i = count; i > 0; --i) {

modules/flann/include/opencv2/flann/timer.h

@@ -60,6 +60,7 @@ public:
      * Constructor.
      */
     StartStopTimer()
+        : startTime(0)
     {
         reset();
     }