useradd.bbclass: remove user/group created by the package in clean* task

At present, if a recipe is built which creates users/groups via
useradd.bbclass, those users/groups are not removed from sysroot
when the recipe/package is cleaned using clean/cleansstate/cleanall
or when a recipe is rebuild and 'unstaged' from the the sysroot.

The "userdel_sysroot_sstate()" provides that functionality.

[YOCTO #9262]

(From OE-Core rev: b5304ce438666a7418746f4ddd32703ae3188089)

Signed-off-by: Maxin B. John <maxin.john@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/sstate.bbclass

@@ -51,6 +51,7 @@ SSTATEPREINSTFUNCS = ""
 SSTATEPOSTUNPACKFUNCS = "sstate_hardcode_path_unpack"
 SSTATEPOSTINSTFUNCS = ""
 EXTRA_STAGING_FIXMES ?= ""
+SSTATECLEANFUNCS = ""
 
 SIGGEN_LOCKEDSIGS_CHECK_LEVEL ?= 'error'
 
@@ -444,6 +445,10 @@ def sstate_clean(ss, d):
                 stfile.endswith(rm_nohash):
             oe.path.remove(stfile)
 
+    # Removes the users/groups created by the package
+    for cleanfunc in (d.getVar('SSTATECLEANFUNCS', True) or '').split():
+        bb.build.exec_func(cleanfunc, d)
+
 sstate_clean[vardepsexclude] = "SSTATE_MANFILEPREFIX"
 
 CLEANFUNCS += "sstate_cleanall"