unictype: Add support for Arabic shaping properties.

unictype: Add support for Arabic shaping properties.

* lib/unictype.in.h (UC_JOINING_TYPE_*): New enumeration values.
(uc_joining_type_name, uc_joining_type_byname, uc_joining_type): New
declarations.
(UC_JOINING_GROUP_*): New enumeration values.
(uc_joining_group_name, uc_joining_group_byname, uc_joining_group): New
declarations.
* lib/gen-uni-tables.c (UC_JOINING_TYPE_*): New enumeration values.
(unicode_joining_type): New variable.
(UC_JOINING_GROUP_*): New enumeration values.
(unicode_joining_group): New variable.
(fill_arabicshaping, joining_type_as_c_identifier,
output_joining_type_test, output_joining_type,
joining_group_as_c_identifier, output_joining_group_test,
output_joining_group): New functions.
(main); Add an argument denoting the ArabicShaping.txt file. Invoke
fill_arabicshaping and output_joining_type_test, output_joining_type,
output_joining_group_test, output_joining_group.
Reported by Simon Josefsson.