At this point I came dangerously close to spewing water all over my keyboard. :D
int greet();
at call site.apt install gcc-dev
cat hello.cs > hello.c
gcc hello.c
gcc -std=gnu89 -m32 -fno-builtin
because GCC defaults to ISO C23 these days, and that will not work, and neither will anything where int and a pointer aren't the same size :)