Fix a memory leak in the Mat copying constructor

Exception may be rasied inside the body of a copying constructor after
refcount has been increased, and beacause in the case of the exception
destrcutor is never called what causes memory leak. This commit adds a
workaround that calls the release() function before the exception is
thrown outside the contructor.

modules/core/src/matrix.cpp

@@ -484,9 +484,12 @@ Mat::Mat(const Mat& m, const Range& _rowRange, const Range& _colRange)
     }
 
     *this = m;
+    try
+    {
         if( _rowRange != Range::all() && _rowRange != Range(0,rows) )
         {
-        CV_Assert( 0 <= _rowRange.start && _rowRange.start <= _rowRange.end && _rowRange.end <= m.rows );
+            CV_Assert( 0 <= _rowRange.start && _rowRange.start <= _rowRange.end
+                       && _rowRange.end <= m.rows );
             rows = _rowRange.size();
             data += step*_rowRange.start;
             flags |= SUBMATRIX_FLAG;
@@ -494,12 +497,19 @@ Mat::Mat(const Mat& m, const Range& _rowRange, const Range& _colRange)
 
         if( _colRange != Range::all() && _colRange != Range(0,cols) )
         {
-        CV_Assert( 0 <= _colRange.start && _colRange.start <= _colRange.end && _colRange.end <= m.cols );
+            CV_Assert( 0 <= _colRange.start && _colRange.start <= _colRange.end
+                       && _colRange.end <= m.cols );
             cols = _colRange.size();
             data += _colRange.start*elemSize();
             flags &= cols < m.cols ? ~CONTINUOUS_FLAG : -1;
             flags |= SUBMATRIX_FLAG;
         }
+    }
+    catch(...)
+    {
+        release();
+        throw;
+    }
 
     if( rows == 1 )
         flags |= CONTINUOUS_FLAG;