meson: fix the missing root mfg flag

The existing meson support missed this root mfg config so that root user
is bypassed. This patch fixed it.

After this change, Redfish/IPMI tests on meson built pacakge starts
working.

Tested:
1. QEMU tests all pass
2. Tested on real hardware, user-manager creats the root user upon
startup. I don't have ldap server but I tested the ldap config APIs
which worked fine.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I57cd2829bc952d8062709b715c88a8efe02c349c
2 files changed