[binutils-gdb] Change type of struct complaints::series

[sergiodj+buildbot@redhat.com]

*** TEST RESULTS FOR COMMIT 05d999b0896ab6ccd4ce23a715765484c60a967d ***

Author: Simon Marchi <simon.marchi@ericsson.com>
Branch: master
Commit: 05d999b0896ab6ccd4ce23a715765484c60a967d

Change type of struct complaints::series
Found while processing the C++ enum changes.  It seems like series
should be of type enum complaint_series, instead of adding a cast.

Redundant and out of date comments are also removed.

gdb/ChangeLog:

	* complaints.c (enum complaint_series): Add newlines and remove
	out of date comment.
	(struct complaints) <series>: Change type to enum
	complaint_series and remove out of date comment.
	(symfile_complaint_hook): Use equivalent enum value
	ISOLATED_MESSAGE instead of 0.