551ceefa4c
Adds four fstab.zram.{25p,50p,75p,none} variants copied to vendor/etc.
init.rpi4.rc activates swap at boot_complete using persist.vendor.zram.size.
Adds vm.min_free_kbytes/lowmem_reserve_ratio memory tuning on init.
SELinux: declares vendor_zram_config_prop for persist.vendor.zram.size.