Fix typo in DWARF 5 line table readers
This typo meant the directory entry was most often zero, which
happened to be sometimes correct anyway (since zero is the compdir).
So for simple testcases it looked correct. But it would be wrong for
compilation units not in the current compdir. Like files compiled with
a relative of absolute path (and then combined into the same compilation
unit with LTO).
The same typo was in both readdwarf.c (read_dwarf2_lineblock) and
readdwarf3.c (read_filename_table). read_dwarf2_lineblock also had
an extra "dwarf" string in the --debug-dump=line output.
https://bugzilla.redhat.com/show_bug.cgi?id=
1927153