[gdb/symtab] Refactor condition in scan_attributes
In scan_attributes there's code:
...
if (new_reader->cu == reader->cu
&& new_info_ptr > watermark_ptr
&& *parent_entry == nullptr)
...
else if (*parent_entry == nullptr)
...
...
that uses the "*parent_entry == nullptr" condition twice.
Make this somewhat more readable by factoring out the condition:
...
if (*parent_entry == nullptr)
{
if (new_reader->cu == reader->cu
&& new_info_ptr > watermark_ptr)
...
else
...
}
...
This also allows us to factor out "form_addr (origin_offset, origin_is_dwz)".