Conan: Delay settings initialization to first use

In practice this could mean "never" in case the step is not used.

Change-Id: I714f2adbe051b6b795d915d56a48900625d258b0
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/conan/conanplugin.cpp

@@ -2,7 +2,6 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
 #include "conaninstallstep.h"
-#include "conansettings.h"
 
 #include <extensionsystem/iplugin.h>
 
@@ -16,7 +15,6 @@ class ConanPlugin final : public ExtensionSystem::IPlugin
 public:
     ConanPlugin()
     {
-        addManaged<ConanSettings>();
         addManaged<ConanInstallStepFactory>();
     }
 };

src/plugins/conan/conansettings.cpp

@@ -9,14 +9,14 @@ using namespace Utils;
 
 namespace Conan::Internal {
 
-static ConanSettings *theSettings;
-
-ConanSettings &settings() { return *theSettings; }
+ConanSettings &settings()
+{
+    static ConanSettings theSettings;
+    return theSettings;
+}
 
 ConanSettings::ConanSettings()
 {
-    theSettings = this;
-
     setSettingsGroup("ConanSettings");
     setAutoApply(false);