gas/Dwarf5: adjust .debug_line file 0 checking

First of all when a table entry has a NULL filename, the two inner if()s
are better done the other way around: The 2nd doesn't depend on what the
first does. This then renders redundant half of the conditions of the
other if() and clarifies that subsequently only entry 0 is dealt with
(indicating that part of the comment was wrong). Finally for there to be
a usable name in slot 1, files_in_use needs to be larger than 1 and slot
1's (rather than slot 0's) name needs to be non-NULL.

0 files changed, 0 insertions, 0 deletions