[glib/kjellahl/turkish-strdown] guniprop: Fix g_utf8_strdown() for Turkish locale

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 2fff80259e4b4adb643523af93e22ea0fb6d2c0d
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Sun Feb 7 15:58:52 2021 +0100

    guniprop: Fix g_utf8_strdown() for Turkish locale
    
    In the Turkish locale the lowercase equivalent of a capital I with dot above
    is a normal lowercase i with a dot above.
    
    Fixes part of issue #390

 glib/guniprop.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/glib/guniprop.c b/glib/guniprop.c
index 619b39908..d6e68397e 100644
--- a/glib/guniprop.c
+++ b/glib/guniprop.c
@@ -1002,6 +1002,11 @@ real_tolower (const gchar *str,
               len += g_unichar_to_utf8 (0x131, out_buffer ? out_buffer + len : NULL); 
             }
         }
+      else if (locale_type == LOCALE_TURKIC && c == 0x130)
+        {
+          /* LATIN CAPITAL LETTER I WITH DOT ABOVE => i (U+0069) */
+          len += g_unichar_to_utf8 (0x0069, out_buffer ? out_buffer + len : NULL);
+        }
       /* Introduce an explicit dot above when lowercasing capital I's and J's
        * whenever there are more accents above. [SpecialCasing.txt] */
       else if (locale_type == LOCALE_LITHUANIAN &&