chore: import upstream snapshot with attribution

cmake/checks/cpu_fp16.cpp

@@ -0,0 +1,34 @@
+#include <stdio.h>
+
+#if defined __F16C__ || (defined _MSC_VER && _MSC_VER >= 1700 && defined __AVX__) || (defined __INTEL_COMPILER && defined __AVX__)
+#include <immintrin.h>
+int test()
+{
+    const float src[] = { 0.0f, 0.0f, 0.0f, 0.0f };
+    short dst[8];
+    __m128 v_src = _mm_load_ps(src);
+    __m128i v_dst = _mm_cvtps_ph(v_src, 0);
+    _mm_storel_epi64((__m128i*)dst, v_dst);
+    return (int)dst[0];
+}
+#elif (defined __GNUC__ && (defined __arm__ || defined __aarch64__)) /*|| (defined _MSC_VER && defined _M_ARM64)*/
+// Windows + ARM64 case disabled: https://github.com/opencv/opencv/issues/25052
+#include "arm_neon.h"
+int test()
+{
+    const float src[] = { 0.0f, 0.0f, 0.0f, 0.0f };
+    short dst[8];
+    float32x4_t v_src = *(float32x4_t*)src;
+    float16x4_t v_dst = vcvt_f16_f32(v_src);
+    *(float16x4_t*)dst = v_dst;
+    return (int)dst[0];
+}
+#else
+#error "FP16 is not supported"
+#endif
+
+int main()
+{
+  printf("%d\n", test());
+  return 0;
+}