fix(tiff): Correctly read TIFF EXIF fields for ExifVersion and FlashPixVersion

[lgritz]

This allows us to correctly read the ExifVersion and FlashPixVersion metadata in an EXIF block of a TIFF file.

[Copilot]

Pull request overview

This pull request fixes the reading of EXIF ExifVersion and FlashPixVersion metadata fields from TIFF files. Previously, these fields were being skipped despite having handler functions defined. The fix adds special-case handling in the TIFF input code to properly read these 4-byte undefined-type fields as strings.

Changes:

• Added special handling in tiffinput.cpp to read ExifVersion and FlashPixVersion as 4-character strings
• Enhanced safe_tiffgetfield to support fields that require passing a count parameter
• Fixed a syntax error and improved type consistency in debug code in exif.cpp
• Updated test reference outputs to reflect the newly-readable metadata fields

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

File	Description
src/tiff.imageio/tiffinput.cpp	Added special case handling for EXIF_EXIFVERSION and EXIF_FLASHPIXVERSION in find_tag(), and extended safe_tiffgetfield() to handle passcount fields
src/tiff.imageio/tiffoutput.cpp	Changed debug output conditionals from #ifndef NDEBUG to #if 0 to unconditionally disable verbose debug messages
src/libOpenImageIO/exif.cpp	Fixed syntax error in debug print statement, changed 200L to 200UL for type consistency, added #ifdef guard for EXIF_TIFF_UTF8, and removed misleading comments about skipping version tags
testsuite/tiff-suite/ref/*.txt	Updated test reference outputs to include the newly-readable Exif:ExifVersion and Exif:FlashPixVersion fields for test images

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[Copilot]

The debug output has been unconditionally disabled by changing from #ifndef NDEBUG to #if 0. This means these debug messages will never be printed, even in debug builds. If this is intentional to reduce noise, consider using a more specific debug flag (like #if DEBUG_TIFF_EXIF) to allow selective enabling when needed for debugging EXIF-related issues.

[Copilot]

Similar to above, this debug output has been unconditionally disabled by changing from commented code to #if 0. Consider using a named debug flag for more granular control if these messages would be useful for debugging EXIF write operations.