fix: switch rockchip family_tweaks from addgroup to groupadd

`addgroup` lives in `adduser`, which Debian forky no longer pulls
into a minimal rootfs by default. `family_tweaks` then dies with
`bash: line 1: addgroup: command not found` (exit 127) on every
forky-armhf rockchip build.

`groupadd` is in `passwd` (Essential, every Linux), and works
identically for our use here. The only behavioural difference —
`groupadd` returns 9 if the group already exists where `addgroup`
returns 0 — is gated by the existing `getent group … ||` guard in
rockchip.conf, and added to rockchip-rv1106.conf to keep
re-runnability.

Repro: armbian/os tinkerboard-current forky-armhf, log
https://paste.armbian.com/iyasuwenum

Author: igorpecovnik

config/sources/families/rockchip-rv1106.conf

@@ -126,9 +126,13 @@ write_uboot_platform() {
 family_tweaks() {
 
 	# Create gpio and i2c groups on the build rootfs; they are matched against
-	# udev rules to allow non-root user access to these resources
-	chroot_sdcard addgroup --system --quiet --gid 900 gpio
-	chroot_sdcard addgroup --system --quiet --gid 901 i2c
+	# udev rules to allow non-root user access to these resources.
+	# `groupadd` (from passwd, Essential) instead of `addgroup` (from
+	# adduser): forky no longer pulls adduser into a minimal rootfs.
+	# `getent group … ||` guard keeps the call idempotent — `groupadd`
+	# exits 9 (vs `addgroup`'s 0) if the group already exists.
+	chroot_sdcard getent group gpio >/dev/null || chroot_sdcard groupadd --system --gid 900 gpio
+	chroot_sdcard getent group i2c  >/dev/null || chroot_sdcard groupadd --system --gid 901 i2c
 
 	return 0
 

config/sources/families/rockchip.conf

@@ -236,9 +236,11 @@ fi
 family_tweaks() {
 
 	# Create gpio and i2c groups on the build rootfs; they are matched against
-	# udev rules to allow non-root user access to these resources
-	chroot_sdcard getent group gpio >/dev/null || chroot_sdcard addgroup --system --quiet --gid 900 gpio
-	chroot_sdcard getent group i2c  >/dev/null || chroot_sdcard addgroup --system --quiet --gid 901 i2c
+	# udev rules to allow non-root user access to these resources.
+	# `groupadd` (from passwd, Essential) instead of `addgroup` (from
+	# adduser): forky no longer pulls adduser into a minimal rootfs.
+	chroot_sdcard getent group gpio >/dev/null || chroot_sdcard groupadd --system --gid 900 gpio
+	chroot_sdcard getent group i2c  >/dev/null || chroot_sdcard groupadd --system --gid 901 i2c
 
 	return 0