atop: new package

atop: new package

Atop is an ASCII full-screen performance monitor for Linux.

- install only the basic functionality (command line tool atop).

- add patch to fix musl build by removing unused include of termio.h.
  Patch was accepted upstream.

Support for extra functionality can be added by follow-up patches:
- init scripts (sysv and systemd) to autostart logging the system
  activity.
- process accounting (needs counterpart enabled in the kernel).

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@datacom.ind.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>