let IsoLangEntry decide how to form a language tag string

Change-Id: I868cd8ea0610b6b8dd8155cdc72f7d238f279ef2

i18npool/inc/i18npool/mslangid.hxx

@@ -180,6 +180,9 @@ public:
         LanguageType  mnLang;
         sal_Char      maLangStr[4];
         sal_Char      maCountry[3];
+
+        /** Obtain a language tag string with '-' separator. */
+        OUString getTagString() const;
     };
 
     /** @internal - Return a pointer to the IsoLangEntry of the underlying table,

i18npool/source/isolang/isolang.cxx

@@ -520,6 +520,14 @@ static MsLangId::IsoLangEntry const aImplIsoLangEntries[] =
 static MsLangId::IsoLangEntry aLastResortFallbackEntry =
 { LANGUAGE_ENGLISH_US, "en", "US" };
 
+OUString MsLangId::IsoLangEntry::getTagString() const
+{
+    if (maCountry[0])
+        return OUString( OUString::createFromAscii( maLangStr) + "-" + OUString::createFromAscii( maCountry));
+    else
+        return OUString::createFromAscii( maLangStr);
+}
+
 // -----------------------------------------------------------------------
 
 // In this table are the countries which should mapped to a specific