android: Don't try to read discovery.xml, it's not needed on mobile.

With this, the actual loolwsd startup does not crash any more, so let's
enable it :-)  Of course it still does not work yet.

Change-Id: I5a1ee7adac64c57f1aa5b597c3dbdc0089a1ac11

android/app/src/main/java/org/libreoffice/androidapp/MainActivity.java

@@ -25,7 +25,7 @@ public class MainActivity extends AppCompatActivity {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
-        //createLOOLWSD();
+        createLOOLWSD();
 
         final WebView browser = findViewById(R.id.browser);
         browser.setWebViewClient(new WebViewClient());

wsd/LOOLWSD.cpp

@@ -2713,12 +2713,11 @@ private:
     /// Process the discovery.xml file and return as string.
     static std::string getDiscoveryXML()
     {
-#if defined __linux && MOBILEAPP
-        // discovery.xml is in the top directory
-        std::string discoveryPath = Path(Application::instance().commandPath()).parent().parent().toString() + "discovery.xml";
+#if MOBILEAPP
+        // not needed for mobile
+        return std::string();
 #else
         std::string discoveryPath = Path(Application::instance().commandPath()).parent().toString() + "discovery.xml";
-#endif
         if (!File(discoveryPath).exists())
         {
             // http://server/hosting/discovery.xml
@@ -2767,6 +2766,7 @@ private:
         DOMWriter writer;
         writer.writeNode(ostrXML, docXML);
         return ostrXML.str();
+#endif
     }
 
     /// Create the /hosting/capabilities JSON and return as string.

wsd/LOOLWSD.hpp

@@ -95,9 +95,14 @@ public:
     /// Return true iff extension is marked as view action in discovery.xml.
     static bool IsViewFileExtension(const std::string& extension)
     {
+#if MOBILEAPP
+        (void) extension;
+        return false; // mark everything editable on mobile
+#else
         std::string lowerCaseExtension = extension;
         std::transform(lowerCaseExtension.begin(), lowerCaseExtension.end(), lowerCaseExtension.begin(), ::tolower);
         return EditFileExtensions.find(lowerCaseExtension) == EditFileExtensions.end();
+#endif
     }
 
     /// Returns the value of the specified application configuration,