Fix ram level alarms (netdata#11452)

Author: ilyam8

health/health.d/ram.conf

@@ -20,8 +20,7 @@ component: Memory
 component: Memory
        os: linux
     hosts: *
-#    calc: $used * 100 / ($used + $cached + $free)
-     calc: ($used - $used_ram_to_ignore) * 100 / ($used  + $cached + $free)
+     calc: ($used - $used_ram_to_ignore) * 100 / ($used + $cached + $free + $buffers)
     units: %
     every: 10s
      warn: $this > (($status >= $WARNING)  ? (80) : (90))
@@ -37,7 +36,7 @@ component: Memory
 component: Memory
        os: linux
     hosts: *
-     calc: ($avail + $system.ram.used_ram_to_ignore) * 100 / ($system.ram.used + $system.ram.cached + $system.ram.free + $system.ram.buffers)
+     calc: $avail * 100 / ($system.ram.used + $system.ram.cached + $system.ram.free + $system.ram.buffers)
     units: %
     every: 10s
      warn: $this < (($status >= $WARNING)  ? (15) : (10))