classes/useradd: handle whitespace only USERADD/GROUPADD/GROUPMEMS
Useradd attempts to add users/groups even when
{USERADD,GROUPADD,GROUPMEMS}_PARAM is whitespace only. This scenario is
possible when variables and modified using one of +=, =+ operator, yet
the content being added is conditional (i.e. may depend on PACKAGECONFIG
flags).
Signed-off-by: Maciej Borzecki <maciej.borzecki@open-rnd.pl> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
