speed up accumulate, accumulateSquare, accumulateProduct and accumulateWeighted using SIMD

  * use SSE and/or AVX based on configuration
  * revise the test to verify the implementation

modules/video/test/test_accum.cpp

@@ -72,11 +72,11 @@ void CV_AccumBaseTest::get_test_array_types_and_sizes( int test_case_idx,
                         vector<vector<Size> >& sizes, vector<vector<int> >& types )
 {
     RNG& rng = ts->get_rng();
-    int depth = cvtest::randInt(rng) % 3, cn = cvtest::randInt(rng) & 1 ? 3 : 1;
-    int accdepth = std::max((int)(cvtest::randInt(rng) % 2 + 1), depth);
+    int depth = cvtest::randInt(rng) % 4, cn = cvtest::randInt(rng) & 1 ? 3 : 1;
+    int accdepth = (int)(cvtest::randInt(rng) % 2 + 1);
     int i, input_count = (int)test_array[INPUT].size();
     cvtest::ArrayTest::get_test_array_types_and_sizes( test_case_idx, sizes, types );
-    depth = depth == 0 ? CV_8U : depth == 1 ? CV_32F : CV_64F;
+    depth = depth == 0 ? CV_8U : depth == 1 ? CV_16U : depth == 2 ? CV_32F : CV_64F;
     accdepth = accdepth == 1 ? CV_32F : CV_64F;
     accdepth = MAX(accdepth, depth);