Open jpegcrop (which can read JPEG JFIF images arithmetically coded by IJG jpeglib's jaricom.c).
Click File / Preferences to open the Preferences dialog box.
Ensure "Entropy Coding Method" is not set to Arithmetic, but instead is set to either "Huffman default" or "Huffman optimized". Click OK.
Click File / Save Frame As, then save as a typical Huffman encoded .jpg.
Besides jpegcrop, any other program built upon the IJG JPEG library (eg, jpegtran) can likely read and/or convert the image -- assuming the library is not excessively old. My primary experience is with the IJG JPEG v8d (circa 2012). Any program/app built on a newer IJG JPEG library than that will very likely work to read/convert images arithmetically encoded by IJG jpeglib's jaricom.c.
To give you an idea of what standards were used, here's some documentation comments from a circa 2012 version of IJG jpeglib's jaricom.c. At the beginning:
"This file contains probability estimation tables for common use in
arithmetic entropy encoding and decoding routines.
This data represents Table D.3 in the JPEG spec (D.2 in the draft),
ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81, and Table 24
in the JBIG spec, ISO/IEC IS 11544 and CCITT Recommendation ITU-T T.82."
then at the end:
"This last entry is used for fixed probability estimate of 0.5
as suggested in Section 10.3 Table 5 of ITU-T Rec. T.851."