[REQUEST] Add djgpp-gcc 9.2.0

The Compiler Explorer now includes the djgpp target, which somehow I hadn't noticed before. First of all I think it's a bit pointless since the generated asm should be identical to other i386 targets, or even x86-64 with -m32. ia16-gcc would be much more interesting :)

Looking through the issue list I see this was requested in #844. A link was given to andrewwutw/build-djgpp which unfortunately hasn't been updated in a while. Please consider using my fork which is capable of building gcc 9.2.0 for djgpp: jwt27/build-gcc, or alternatively a more generic i386-elf with newlib.