This is a fork of GDB 7.1a, one of the last known "good" versions of GDB that can still load coff-go32 executables as generated by DJGPP.
This fork produces an executable specifically for the i586-pc-msdosdjgpp target needed to debug DJGPP applications.
The fork is supposed to compile with the latest MinGW on Windows, GCC on Linux, and Clang shipping with Xcode on macOS.
Install autoconf via brew, Xcode from the app store. Then:
./configure --target=i586-pc-msdosdjgpp --disable-werror
make -j8
The gdb executable can then be found in the gdb/ folder.
Get Msys/MinGW64 and ensure you have autoconf and gcc installed. Then:
./configure --target=i586-pc-msdosdjgpp --disable-werror
make -j8