Merge pull request #21107 from take1014:remove_assert_21038

resolves #21038

* remove C assert

* revert C header

* fix several points in review

* fix test_ds.cpp

modules/ml/src/precomp.hpp

@@ -48,7 +48,6 @@
 
 #include "opencv2/core/private.hpp"
 
-#include <assert.h>
 #include <float.h>
 #include <limits.h>
 #include <math.h>

modules/ml/src/tree.cpp

@@ -869,7 +869,7 @@ DTreesImpl::WSplit DTreesImpl::findSplitCatClass( int vi, const vector<int>& _si
     }
     else
     {
-        assert( m == 2 );
+        CV_Assert( m == 2 );
         dbl_ptr = (double**)(c_weights + _mi);
         for( j = 0; j < mi; j++ )
             dbl_ptr[j] = cjk + j*2 + 1;