fix android pack build

cmake/OpenCVCompilerOptions.cmake

@@ -369,3 +369,18 @@ if(MSVC)
     ocv_warnings_disable(CMAKE_CXX_FLAGS /wd4589) # Constructor of abstract class 'cv::ORB' ignores initializer for virtual base class 'cv::Algorithm'
   endif()
 endif()
+
+if(NOT OPENCV_FP16_DISABLE)
+  try_compile(__VALID_FP16
+    "${OpenCV_BINARY_DIR}"
+    "${OpenCV_SOURCE_DIR}/cmake/checks/fp16.cpp"
+    COMPILE_DEFINITIONS "-DCHECK_FP16"
+    OUTPUT_VARIABLE TRY_OUT
+    )
+  if(NOT __VALID_FP16)
+    message(STATUS "FP16: Compiler support is not available")
+  else()
+    message(STATUS "FP16: Compiler support is available")
+    set(HAVE_FP16 1)
+  endif()
+endif()

cmake/checks/fp16.cpp

@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+#if defined __F16C__ || (defined _MSC_VER && _MSC_VER >= 1700)
+#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__)
+#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;
+}

cmake/templates/cvconfig.h.in

@@ -203,3 +203,6 @@
 
 /* Lapack */
 #cmakedefine HAVE_LAPACK
+
+/* FP16 */
+#cmakedefine HAVE_FP16