sadc/sar: New /proc/meminfo fields to memory statistics

Five new fields have been added to memory statistics displayed by sar.
These new fields are part of A_MEMORY activity and will be displayed
using option "-r ALL" with sar.
No layout format incompatible change with this patch: The datafile
created by this version of sar can still be read by a previous version
of sar (though the new fields won't be displayed of course as they are
unknown by this old version).
Various outputs from sadf (JSON, XML, etc.) have been updated to take
into account these new metrics.

Originally suggested by Peter Portante (@portante).

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>