Zero initialize ExifMnoteData<vendor> during construction with exif_mnote_data_<vendor>_new. am: c9da78d8d9

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libexif/+/16248754

Change-Id: I245ad60a134ec9fe65a7f8b4c83a78193f875dd0