Bug 11927 - Add greek chr lang_def file

Bug 11927 - Add greek chr lang_def file

Add the sort-string-utf.chr for sorting Greek catalog (it can also contain latin records).

Developped in collaboration with Giannis Kourmoulis <ikourmou@lib.auth.gr>

Test plan :
- Install using "gr" in "Primary language for Zebra indexing"
- Index a greek catalog
- Sort by title and check sorting is correct

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>