Improved jpeg decoding code with exif

[vfdev-5]

Follow-up to #8279

Description:

• Added missing JPEG_FOUND flag in exif.h to properly handle situations when jpg is not present on the system
• Replaced std::vector with a reader (inspired from PNG decoder code)

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/vision/8302

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 1 New Failure

As of commit 64166d0 with merge base f3298dc ():

NEW FAILURE - The following job has failed:

• Tests / unittests-windows (3.11, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[NicolasHug]

Thanks @vfdev-5 , one Q below but I'll let you decide on it, LGTM

[github-actions]

Hey @vfdev-5!

You merged this PR, but no labels were added.
The list of valid labels is available at https://github.com/pytorch/vision/blob/main/.github/process_commit.py