As discussed in the thread starting at:

  https://gcc.gnu.org/pipermail/gcc/2024-June/244199.html

it would be useful to have the @gcc.gnu.org bugzilla account names
in MAINTAINERS.  This is because:

(a) Not every non-@gcc.gnu.org email listed in MAINTAINERS is registered
    as a bugzilla user.

(b) Only @gcc.gnu.org accounts tend to have full rights to modify tickets.

(c) A maintainer's name and email address aren't always enough to guess
    the bugzilla account name.

(d) The users list on bugzilla has many blank entries for "real name".

However, including @gcc.gnu.org to the account name might encourage
people to use it for ordinary email, rather than just for bugzilla.
This patch goes for the compromise of using the unqualified account
name, with some text near the top of the file to explain its usage.

There isn't room in the area maintainer sections for a new column,
so it seemed better to have the account name only in the Write
After Approval section.  It's then necessary to list all maintainers
there, even if they have more specific roles as well.

Also, there were some entries that didn't line up with the
prevailing columns (they had one tab too many or one tab too few).
It seemed easier to check for and report this, and other things,
if the file used spaces rather than tabs.

There was one instance of an email address without the trailing ">".
The updates to check-MAINTAINERS.py includes a test for that.

The account names in the file were taken from a trawl of the
gcc-cvs archives, with a very small number of manual edits for
ambiguities.  There are a handful of names that I couldn't find;
the new column has "-" for those.  The names were then filtered
against the bugzilla @gcc.gnu.org user list, with those not
present again being blanked out with "-".

ChangeLog:
	* MAINTAINERS: Replace tabs with spaces.  Add a bugzilla account
	name column to the Write After Approval section.  Line up the
	email column and fix an entry that was missing the trailing ">".

contrib/ChangeLog:
	* check-MAINTAINERS.py (sort_by_surname): Replace with...
	(get_surname): ...this.
	(has_tab, is_empty): Delete.
	(check_group): Take a list of column positions as argument.
	Check that lines conform to these column numbers.  Check that the
	final column is an email in angle brackets.  Record surnames on
	the fly.
	(top level): Reject tabs.  Use paragraph counts to identify which
	groups of lines should be checked.  Report missing sections.