message: Update Froxelizer.h
  Fix this error when building with msvc from vs2019
  error C2926:  'filament::details::Froxelizer::FroxelEntry::<unnamed-tag>::offset': a default member initializer is not allowed for a member of an anonymous struct within a union
diff: @@ -145,11 +145,11 @@ public:
  struct FroxelEntry {
  union {
  - uint32_t u32;
  + uint32_t u32 = 0;
  struct {
  - uint16_t offset = 0;
  + uint16_t offset;
  union {
  - uint8_t count[2] = { 0, 0 };
  + uint8_t count[2];
  struct {
  uint8_t pointLightCount;
  uint8_t spotLightCount;
  