i18n examples: Add en translation dummies

We endorse using QTranslator::install(const QLocale&...), because
it tries loading translations from all QLocale::uiLanguages() instead
of the commonly used QLocale::system().name() setup.

Anyhow, the first method requires an English translation - otherwise
a second favorite language might be used.

Pave the way to making the switch by adding (empty) English translations
to our examples.

Task-number: QTBUG-69196
Change-Id: Ie85be875e34e29e80c1693bbf477b962e35a7d87
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

examples/qml/qml-i18n/i18n/qml_en.ts

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE TS>
+<TS version="2.1" language="en" sourcelanguage="en">
+</TS>

examples/quick/demos/photoviewer/i18n/qml_en.ts

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE TS>
+<TS version="2.1" language="en">
+</TS>

examples/quick/demos/photoviewer/photoviewer.pro

@@ -10,7 +10,8 @@ SOURCES = *.qml \
           PhotoViewerCore/script/*.js
 }
 
-TRANSLATIONS += i18n/qml_fr.ts \
+TRANSLATIONS += i18n/qml_en.ts \
+                i18n/qml_fr.ts \
                 i18n/qml_de.ts
 
 RESOURCES += qml.qrc

examples/quick/demos/photoviewer/qml.qrc

@@ -15,5 +15,6 @@
         <file>PhotoViewerCore/script/script.js</file>
         <file>i18n/qml_fr.qm</file>
         <file>i18n/qml_de.qm</file>
+        <file>i18n/qml_en.qm</file>
     </qresource>
 </RCC>