Allow init to execute extra_free_kbytes.sh script

extra_free_kbytes.sh is used by init to set /sys/vm/watermark_scale_factor
value. Allow init to execute extra_free_kbytes.sh and the script to access
/proc/sys/vm/watermark_scale_factor and /proc/sys/vm/extra_free_kbytes
files.

Bug: 109664768
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I55ec07e12a1cc5322cfdd4a48d0bdc607f45d832
diff --git a/private/extra_free_kbytes.te b/private/extra_free_kbytes.te
new file mode 100644
index 0000000..af3088b
--- /dev/null
+++ b/private/extra_free_kbytes.te
@@ -0,0 +1,3 @@
+typeattribute extra_free_kbytes coredomain;
+
+init_daemon_domain(extra_free_kbytes)