I spotted a few misplaced entries in the ChangeLog-2019 entries, and
went on to fix them.
Looking around I saw a good number of other entries in other years.
Then OCD got the best of me and I fixed them all.
Also fixes cases of wrong paths in entries, like "* gdb/foo.c" instead
of "* foo.c".
gdb/ChangeLog:
* ChangeLog-2010: Renames ChangeLog.
* ChangeLog: New file.
* config/djgpp/fnchange.lst: Add exception for gdb/ChangeLog-2010.
Also fix a typo in the exception for gdb/ChangeLog-2009.