fix reshape call not being an inplace method

fixes #5853 #4740

modules/ml/src/em.cpp

@@ -198,7 +198,7 @@ public:
             sample.convertTo(tmp, CV_64FC1);
             sample = tmp;
         }
-        sample.reshape(1, 1);
+        sample = sample.reshape(1, 1);
 
         Mat probs;
         if( _probs.needed() )
@@ -342,7 +342,7 @@ public:
         if(weights0 && (startStep == START_E_STEP && covs0))
         {
             weights0->convertTo(weights, CV_64FC1);
-            weights.reshape(1,1);
+            weights = weights.reshape(1,1);
             preprocessProbability(weights);
         }