The iso8859-1 Compose table includes an optional section which uses
Ctrl<T> as a substitute for <Multi_key>.  In that section the sequence
to generate an @ (at) either was incorrectly copied from the Multi_key
section or was not kept in sync with the Multi_key section.

Fixing this eliminates the warning from compose-check.pl:

┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
┃ Clash with existing sequence in iso8859-1/Compose.pre
┃  on line 661: Ctrl<T> <A> <A>
┃    line #661: Ctrl<T> <A> <A>		: "\305"	Aring
┃    line #480: Ctrl<T> <A> <A>		: "@"	at
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Signed-off-by: James Cloos <cloos@jhcloos.com>