Default legacy log launch to on, and limit it to platforms it works on(windows) at compile time.

indra/newview/app_settings/settings.xml

@@ -717,7 +717,7 @@
       <key>Type</key>
       <string>Boolean</string>
       <key>Value</key>
-      <boolean>0</boolean>
+      <boolean>1</boolean>
     </map>
     <key>LiruLegacyOutfitStoreObjChanges</key>
     <map>

indra/newview/llimpanel.cpp

@@ -995,11 +995,13 @@ void LLFloaterIMPanel::onFlyoutCommit(LLComboBox* flyout, const LLSD& value)
 
 void show_log_browser(const std::string& name, const std::string& id)
 {
+#if LL_WINDOWS // Singu TODO: Other platforms?
 	if (gSavedSettings.getBOOL("LiruLegacyLogLaunch"))
 	{
 		gViewerWindow->getWindow()->ShellEx("\"" + LLLogChat::makeLogFileName(name) + "\"");
 		return;
 	}
+#endif
 	LLFloaterWebContent::Params p;
 	p.url("file:///" + LLLogChat::makeLogFileName(name));
 	p.id(id);