Reformat ctype.c

Reformat ctype.c

Enhance the readability of ctype.c by using an enum instead of macros
to initialize the character class table.  This allows the use of a single
letter to mark a char, making the table fit within 80 columns.

Also list the index of the last entry in each row in the following comment.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>