Apple: Use 'en' instead of 'English' as development region

This is consistent with what $(DEVELOPMENT_LANGUAGE) reports, as well as
the Apple Locales Programming Guide which states that "Locale names such
as “English”, “French”, and “Japanese” are deprecated in OS X and are
supported solely for backward compatibility."

Pick-to: 6.4
Change-Id: I99779d678ef9d4ea90249572f2f977e9b4df6c62
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

cmake/macos/MacOSXBundleInfo.plist.in

@@ -29,7 +29,7 @@
 	<string>${MACOSX_BUNDLE_ICON_FILE}</string>
 
 	<key>CFBundleDevelopmentRegion</key>
-	<string>English</string>
+	<string>en</string>
 
 	<key>NSPrincipalClass</key>
 	<string>NSApplication</string>

mkspecs/macx-clang/Info.plist.app

@@ -21,6 +21,6 @@
 	<key>NSSupportsAutomaticGraphicsSwitching</key>
 	<true/>
 	<key>CFBundleDevelopmentRegion</key>
-	<string>English</string>
+	<string>en</string>
 </dict>
 </plist>

tests/manual/ios_assets/Info.ios.cmake.plist

@@ -33,7 +33,7 @@
     <string></string>
 
     <key>CFBundleDevelopmentRegion</key>
-    <string>English</string>
+    <string>en</string>
 
     <key>LSRequiresIPhoneOS</key>
     <true/>