In function ‘afslog_cell.isra’:
afslog.c:144:13: warning: ‘%s’ directive argument is null [-Wformat-overflow=]
144 | warnx("No cell matching \"%s\" found.", cell);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
caused by expand_cell_name() returning the input pointer.
Alter the behavior of expand_cell_name() to match its usage.
Change-Id: I3b15c4b3e59b597af5351e5e62f5d7751be50feb