Fix build warning on Tizen 6.0

Fix build warning on Tizen 6.0

[    8s] In file included from /usr/include/string.h:494,
[    8s]                  from /home/abuild/rpmbuild/BUILD/libsyscommon-4.1/src/libgdbus/dbus-systemd.c:21:
[    8s] In function 'strncpy',
[    8s]     inlined from 'systemd_get_unit_dbus_path' at /home/abuild/rpmbuild/BUILD/libsyscommon-4.1/src/libgdbus/dbus-systemd.c:386:2:
[    8s] /usr/include/bits/string_fortified.h:106:10: warning: '__builtin_strncpy' output truncated before terminating nul copying 31 bytes from a string of the same length [-Wstringop-truncation]
[    8s]   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));

Change-Id: Iaf5f71d7c364db91b495f50e63005778765ba359