flo: Enable ZRAM

I have backported enough kernel stuff to align our implementation
with android-3.10.
Use ~500MB disk, 4 compression streams, lz4 compression.

Change-Id: I82ee5c43aefb732ee603bdf1ae190e5e9936e660

fstab.flo

@@ -24,3 +24,4 @@
 /dev/block/platform/msm_sdcc.1/by-name/rpmb         /rpmb           emmc    defaults                                                                     defaults
 /dev/block/platform/msm_sdcc.1/by-name/abootb       /abootb         emmc    defaults                                                                     defaults
 /devices/platform/msm_hsusb_host/usb*               auto            auto    defaults                                                                     voldmanaged=usb:auto
+/dev/block/zram0                                    none            swap    defaults                                                                     zramsize=533413200,max_comp_streams=4,notrim

init.flo.rc

@@ -30,8 +30,13 @@ on init
     mkdir /persist 0771 system system
     mkdir /firmware 0771 system system
 
+    # ZRAM setup
+    write /sys/block/zram0/comp_algorithm lz4
+    write /proc/sys/vm/page-cluster 0
+
 on fs
     mount_all ./fstab.flo
+    swapon_all ./fstab.flo
     restorecon_recursive /persist
     write /sys/kernel/boot_adsp/boot 1
 
@@ -82,8 +87,6 @@ on boot
     # Enable DEBUG_SUSPEND, DEBUG_EXIT_SUSPEND, and DEBUG_WAKEUP
     write /sys/module/wakelock/parameters/debug_mask 7
 
-    write /proc/sys/vm/swappiness 0
-
     #To allow interfaces to get v6 address when tethering is enabled
     write /proc/sys/net/ipv6/conf/rmnet0/accept_ra 2
     write /proc/sys/net/ipv6/conf/rmnet1/accept_ra 2

sepolicy/file_contexts

@@ -40,6 +40,8 @@
 /dev/block/platform/msm_sdcc\.1/by-name/userdata u:object_r:userdata_block_device:s0
 # encryption metadata
 /dev/block/platform/msm_sdcc\.1/by-name/metadata u:object_r:metadata_block_device:s0
+# zram block labeling
+/dev/block/zram0                       u:object_r:swap_block_device:s0
 
 # CPU governor controls
 /dev/socket/mpdecision(/.*)?           u:object_r:mpdecision_socket:s0