library/PCUIF_Types.ttcn: mark PCUIF_Text as 'null_terminated'

This is a TITAN specific attribute that allows to indicate that
a field of type 'charstring' is '\0'-terminated. Without that
attribute, 'PCUIF_Text' is mixed with the padding characters:

  "0.7.0.5-df0f" & char(0, 0, 0, 0) & char(0, 0, 0, 0) & ...

Change-Id: Ic81fff4c82871bb29a2385b9ee7a2dd98f67dfb0
diff --git a/library/PCUIF_Types.ttcn b/library/PCUIF_Types.ttcn
index 27d9b92..f13a764 100644
--- a/library/PCUIF_Types.ttcn
+++ b/library/PCUIF_Types.ttcn
@@ -70,7 +70,7 @@
 	PCU_OML_ALERT			(1)
 } with { variant "FIELDLENGTH(8)" };
 
-type charstring PCUIF_Text length(128) with { variant "FIELDLENGTH(128)" };
+type charstring PCUIF_Text length(128) with { variant "FIELDLENGTH(null_terminated)" };
 
 type record PCUIF_txt_ind {
 	PCUIF_TextType	txt_type,