add windows native aligned malloc + unit test case

* implements https://github.com/opencv/opencv/issues/19147
* CAUTION: this PR will only functions safely in the
  4+ branches that already include PR 19029
* CAUTION: this PR requires thread-safe startup of the alloc.cpp
  translation unit as implemented in PR 19029

modules/core/test/test_misc.cpp

@@ -2,6 +2,7 @@
 // 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.
 #include "test_precomp.hpp"
+#include <cmath>
 
 namespace opencv_test { namespace {
 
@@ -783,5 +784,18 @@ TEST(Core_Check, testSize_1)
     }
 }
 
+TEST(Core_Allocation, alignedAllocation)
+{
+    // iterate from size=1 to approximate byte size of 8K 32bpp image buffer
+    for (int i = 0; i < 200; i++) {
+        const size_t size = static_cast<size_t>(std::pow(1.091, (double)i));
+        void * const buf = cv::fastMalloc(size);
+        ASSERT_NE((uintptr_t)0, (uintptr_t)buf)
+            << "failed to allocate memory";
+        ASSERT_EQ((uintptr_t)0, (uintptr_t)buf % CV_MALLOC_ALIGN)
+            << "memory not aligned to " << CV_MALLOC_ALIGN;
+        cv::fastFree(buf);
+    }
+}
 
 }} // namespace