syscallinfo: fix typo for oldlstat

[kkourt]

There seems to be a typo for SYS_OLDLSTAT. The name should be oldlstat rather than oldstat.

Looking at the i386/linux.go file:

$ grep -e 'OLDL\?STAT' ./pkg/syscallinfo/i386/linux.go
        SYS_OLDSTAT                      = 18
        SYS_OLDLSTAT                     = 84

Verified the number with:

$ cat oldlstat.c
int main(int argc, char **argv)
{
        printf("SYS_oldlstat:%d\n", SYS_oldlstat);
        return 0;
}
$ gcc -Wall -m32 oldlstat.c -o oldlstat
$ ./oldlstat
SYS_oldlstat:84