Hi Linh,
gcc -fPIE -Wl,-z,relro -Wl,-z,now runguard.o /usr/lib/libm.so -o runguard /usr/lib/libm.so: could not read symbols: File in wrong format
I've never seen that before. It suggests that there's something wrong with your system. Did you by any chance install e.g. 32 bit packages on a 64 bit OS installation, or the other way around?
I propose using Google to find out more about this error because it's not DOMjudge related.
Cheers, Thijs