Out-of-bounds read in TONYC Imager

Summary

Imager versions from 0.45_02 before 1.034 for Perl may expose adjacent heap bytes via strlen() over-read from zero-count ASCII EXIF entries in copy_string_tags. copy_string_tags() computes an ASCII EXIF tag's length as `entry->size - 1` to strip the trailing NUL. A zero-count ASCII entry sets `entry->size` to 0, and the derived length reaches i_tags_add() as -1, which is interpreted as a request to call strlen(), scanning past the entry to the next NUL and copying those bytes into the tag. JPEG reaches this path via im_decode_exif(), as does the separate Imager::File::WEBP distribution, which is fixed by upgrading Imager. Any caller of Imager->read() on an attacker-supplied image with such an entry may receive an exif_* tag holding adjacent heap bytes instead of an empty string.