core(ocl): fix deadlock in UMatDataAutoLock

UMatData locks are not mapped on real locks (they are mapped to some "pre-initialized" pool).

Concurrent execution of these statements may lead to deadlock:
- a.copyTo(b) from thread 1
- c.copyTo(d) from thread 2
where:
- 'a' and 'd' are mapped to single lock "A".
- 'b' and 'c' are mapped to single lock "B".

Workaround is to process locks with strict order.

modules/core/src/umatrix.hpp

@@ -0,0 +1,20 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+#ifndef OPENCV_CORE_SRC_UMATRIX_HPP
+#define OPENCV_CORE_SRC_UMATRIX_HPP
+
+namespace cv {
+
+struct CV_EXPORTS UMatDataAutoLock
+{
+    explicit UMatDataAutoLock(UMatData* u);
+    UMatDataAutoLock(UMatData* u1, UMatData* u2);
+    ~UMatDataAutoLock();
+    UMatData* u1;
+    UMatData* u2;
+};
+
+}
+
+#endif // OPENCV_CORE_SRC_UMATRIX_HPP