incorrect calculation of the esym in multiboot.c

In the function copy_syms, the kernel copies the symtab and the strtab
somewhere after the end and then saves the final end to esym.

But, in the real code, the esym just gets the end of the strtab but
not the final end, because the symtab will follow the strtab in some
cases.

The code conflicts with the comments above, right?

Thanks for any tips.