Cope with Qt 5.14's dropping of the MIME type DB as a resource

The copy is still present on non-Linux systems, but is not accessible as
a resource, so we must ship our own copy.

Fixes: QTCREATORBUG-22636
Change-Id: Ie7ae7616eadf4035bec6fffd15ac303c1d2badce
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/3rdparty/xdg/README

@@ -0,0 +1,7 @@
+This contains a copy of freedesktop.org's shared-mime-info base package.
+
+Update instructions:
+
+  curl https://people.freedesktop.org/~hadess/shared-mime-info-{VERSION}.tar.xz | \
+  xzcat | \
+  tar -xO shared-mime-info-{VERSION}/freedestop.org.xml > freedesktop.org.xml

src/libs/utils/mimetypes/mimeprovider.cpp

@@ -789,16 +789,9 @@ void MimeXMLProvider::ensureLoaded()
                                                          QStandardPaths::LocateFile);
 
         if (allFiles.isEmpty()) {
-            // System freedesktop.org.xml file not found, try to use the one in QtCore.
+            // System freedsktop.org.xml file not found, use our bundled copy
-            // This is private API and has changed in the past:
+            const char freedesktopOrgXml[] = ":/utils/mimetypes/freedesktop.org.xml";
-            // - Qt 5.11 added "package" subdir in 7a5644d6481a3c1a7416772998ca4e60c977bfbd
+            allFiles.prepend(QLatin1String(freedesktopOrgXml));
-            // - Qt 5.13 added an option to not bundle it at all
-            const QString fdoXml5_11 = QStringLiteral(":/qt-project.org/qmime/packages/freedesktop.org.xml");
-            if (QFile::exists(fdoXml5_11))
-                allFiles << fdoXml5_11;
-            else
-                qFatal("Utils::MimeXMLProvider: could not find the system freedesktop.org.xml file "
-                       "and QtCore does not have an accessible copy.");
         }
 
         m_nameMimeTypeMap.clear();

src/libs/utils/utils.qrc

@@ -223,6 +223,7 @@
         <file>images/toggleprogressdetails@2x.png</file>
         <file>images/unknownfile.png</file>
         <file>images/dir.png</file>
+        <file alias="mimetypes/freedesktop.org.xml" compression-algorithm="best">../3rdparty/xdg/freedesktop.org.xml</file>
     </qresource>
     <qresource prefix="/codemodel">
         <file>images/enum.png</file>