seriously improved performance of blur function, especially 3x3 and 5x5 cases (#7262)

* seriously improved performance of blur function, especially 3x3 and 5x5 cases

* trying to fix warnings and test failures

* replaced #if 0 with #if IPP_DISABLE_BLOCK

modules/imgproc/perf/perf_blur.cpp

@@ -100,9 +100,7 @@ PERF_TEST_P(Size_MatType_BorderType, blur16x16,
     BorderType btype = get<2>(GetParam());
     double eps = 1e-3;
 
-#if CV_NEON
     eps = CV_MAT_DEPTH(type) <= CV_32S ? 1 : eps;
-#endif
 
     Mat src(size, type);
     Mat dst(size, type);