logswan: update to 2.1.1.

Logswan 2.1.1 (2019-10-30)

- Check if system has seccomp in CMakeLists.txt
- Use the HAVE_SECCOMP macro to check whether or not to enable seccomp
- Define and use a GEOIP2DB macro to specify GeoLite2 database name
- Add a switch (-d) to allow specifying path to a GeoIP2 database file
- Define and use a LOGSWAN_SYSCALL_ALLOW macro to make code more readable
- Adding missing #include guard in seccomp.h header file
- Use __NR_ instead of SYS_ prefix in LOGSWAN_SYSCALL_ALLOW
- Fix the build on aarch64 Linux, where the open() syscall does not exist
- Add error checking for both prctl() calls

(fcambus)