Alignment mark generation fails due to activating #define STBI_ONLY_JPEG

[caco3]

    @caco3 also got this `E (95242) C IMG BASIS: Failed to load /sdcard/img_tmp/ref0_org_org.jpg! Is it corrupted?` in rolling 4b23e0c

Originally posted by @stefan123t in #1720 (comment)

[caco3]

It seems to have got broken with #1713
With #1711 it is still ok

[Slider0007]

This commit seems to break it: 2ce2575 --> PR #1706

[caco3]

I could trace it down to only this line: STBI_ONLY_JPEG

It looks like as if the alignment mark generation uses something else than JPEG.

This most probably could be changed. Until then, I revert that line.