[php-src] PR #24722: Fuzz exif thumbnail handling

Pull Request: https://github.com/php/php-src/pull/24722 Author: yumasansansan php-fuzz-exif calls exif_read_data($stream) with the default arguments. With $read_thumbnail = false, the thumbnail is never extracted (ImageInfo->read_thumbnail gates several code paths in ext/exif/exif.c), and exif_thumbnail() is not called at all. The fuzzer now calls exif_read_data($stream, null, false, true) and exif_thumbnail($stream, $width, $height, $type). Passing $width/$height makes exif_thumbnail() call exif_scan_thumbnail(). Replaying the checked-in sapi/fuzzer/corpus/exif (no fuzzing): | Function | Before (edges) | After (edges) | |---|---|---| | zif_exif_thumbnail | not reached | 13/45 | | exif_thumbnail_build | not reached | 29/73 | | exif_thumbnail_extract | not reached | 3/11 | | exif_thumbnail_in_file | not reached | 2/4 | | exif_scan_thumbnail | 2/48 | 8/48 | The input format is unchanged, existing corpora stay valid.