Bug#3848: make the output of lib/mkchartable.pl v2.4 compatible

Apparently I have backported too much from the master-branch, I
wanted to have just the charset-aliases.  In turn, the generated
lib/chartable.c was then very different.  With this fix lib/chartable.c
is almost the same as before commit 63856fcdf .
Bug#3848 lib/charset/aliases.txt: add latin1 as alias of iso-9959-1
sieve/sieve.y: fix comment

In "vu should call yyerror" vu is supposed to mean verify_utf8, but
here verify_address (=va) is the function, which would call yyerror.