Use "en-US" as the default for XHP's xml-lang attribute.

Change-Id: I765e1cc25ac79d2cebf54f7a247a200647c984da
Reviewed-on: https://gerrit.libreoffice.org/32296Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
Tested-by: Olivier Hallot <olivier.hallot@libreoffice.org>

cui/source/dialogs/screenshotannotationdlg.cxx

@@ -54,7 +54,7 @@ namespace
 
     OUString lcl_AltDescr()
     {
-        OUString aTempl = OUString("<alt xml-lang=\"en-US\" id=\"%1\">"
+        OUString aTempl = OUString("<alt id=\"%1\">"
                                    " " //FIXME real dialog title or something
                                   "</alt>");
         aTempl = aTempl.replaceFirst( "%1", lcl_genRandom("alt_id") );
@@ -79,7 +79,7 @@ namespace
 
     OUString lcl_ParagraphWithImage( const OUString& rScreenshotId, const Size& rSize )
     {
-        OUString aTempl = OUString( "<paragraph id=\"%1\" role=\"paragraph\" xml-lang=\"en-US\">%2"
+        OUString aTempl = OUString( "<paragraph id=\"%1\" role=\"paragraph\">%2"
                                     "</paragraph>"  SAL_NEWLINE_STRING );
         aTempl = aTempl.replaceFirst( "%1", lcl_genRandom("par_id") );
         aTempl = aTempl.replaceFirst( "%2", lcl_Image(rScreenshotId, rSize) );
@@ -90,7 +90,7 @@ namespace
     OUString lcl_Bookmark( const OUString& rWidgetId )
     {
         OUString aTempl = "<!-- Bookmark for widget %1 -->" SAL_NEWLINE_STRING
-                          "<bookmark xml-lang=\"en-US\" branch=\"hid/%2\" id=\"%3\" localize=\"false\"/>" SAL_NEWLINE_STRING;
+                          "<bookmark branch=\"hid/%2\" id=\"%3\" localize=\"false\"/>" SAL_NEWLINE_STRING;
         aTempl = aTempl.replaceFirst( "%1", rWidgetId );
         aTempl = aTempl.replaceFirst( "%2", rWidgetId );
         aTempl = aTempl.replaceFirst( "%3", lcl_genRandom("bm_id") );

l10ntools/source/xmlparse.cxx

@@ -330,7 +330,7 @@ void XMLFile::Extract()
 
 void XMLFile::InsertL10NElement( XMLElement* pElement )
 {
-    OString sId, sLanguage("");
+    OString sId, sLanguage("en-US");
     LangHashMap* pElem;
 
     if( pElement->GetAttributeList() != nullptr )
@@ -445,7 +445,8 @@ void XMLFile::SearchL10NElements( XMLChildNode *pCur )
                 bool bInsert = true;
                 XMLElement *pElement = static_cast<XMLElement*>(pCur);
                 const OString sName(pElement->GetName().toAsciiLowerCase());
-                OString sLanguage, sTmpStrVal;
+                OString sLanguage("en-US");
+                OString sTmpStrVal;
                 if ( pElement->GetAttributeList())
                 {
                     for ( size_t j = 0 , cnt = pElement->GetAttributeList()->size(); j < cnt && bInsert; ++j )
@@ -603,11 +604,18 @@ void XMLElement::ChangeLanguageTag( const OString &rValue )
     SetLanguageId(rValue);
     if ( m_pAttributes )
     {
+        bool bWasSet = false;
         for (size_t i = 0; i < m_pAttributes->size(); ++i)
         {
-            if ( (*m_pAttributes)[ i ]->GetName() == "xml-lang" )
+            if ((*m_pAttributes)[ i ]->GetName() == XML_LANG)
+            {
                 (*m_pAttributes)[ i ]->setValue(rValue);
+                bWasSet = true;
+            }
         }
+
+        if (!bWasSet)
+            AddAttribute(XML_LANG, rValue);
     }
     XMLChildNodeList* pCList = GetChildList();
 
@@ -681,7 +689,7 @@ void XMLElement::Print(XMLNode *pCur, OStringBuffer& rBuffer, bool bRootelement
                             for ( size_t j = 0; j < pElement->GetAttributeList()->size(); j++ )
                             {
                                 const OString aAttrName( (*pElement->GetAttributeList())[ j ]->GetName() );
-                                if( !aAttrName.equalsIgnoreAsciiCase( "xml-lang" ) )
+                                if (!aAttrName.equalsIgnoreAsciiCase(XML_LANG))
                                 {
                                     rBuffer.append(
                                         " " + aAttrName + "=\"" +