ts: refactor OpenCV tests

- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers

modules/core/perf/opencl/perf_dxt.cpp

@@ -49,7 +49,7 @@
 
 #ifdef HAVE_OPENCL
 
-namespace cvtest {
+namespace opencv_test {
 namespace ocl {
 
 ///////////// dft ////////////////////////
@@ -113,6 +113,6 @@ OCL_PERF_TEST_P(MulSpectrumsFixture, MulSpectrums,
     SANITY_CHECK(dst, 1e-3);
 }
 
-} } // namespace cvtest::ocl
+} } // namespace opencv_test::ocl
 
 #endif // HAVE_OPENCL