The compilers are all updated in Ubuntu 18.04 basesystem.
Add some defines for judger on compiling and replace web's display version to the real version.
To support new compilers we must modify the syscall list to let them run properly, otherwise they will error with "Dangerous Syscalls".
The Oracle JDK8 will read usagetracker profiles and record usage infomation, so disable it in order to not making junk files which may cause DGS.
Due to historic reasons, the version and path of compilers are specified.
This will remove these specifications to make judger more adaptable.
Also provide defines to specify new version and keep for default.