Fix reading environment variables with newline
Summary:
Use '\0' as separator as '\n' is likely to appear in values.
BUG: 413130
Test Plan:
/etc/profile.d/mc.sh exported an mc() function,
which resulted in "syntax error: unexpected end of file" in the Plasma session.
Now the mc function is correctly set in the environment.
Reviewers: Plasma, apol, davidedmundson, adridg
Reviewed By: Plasma, apol, davidedmundson, adridg
Subscribers: davidedmundson, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D24750