BuildManager: Provide context of earlier build steps to init

This information can be used to get information from earlier steps,
which e.g. queried for android devices to deploy to.

Change-Id: Iefe1c9443915cb6211f86f98ff7aaf3cb75145ba
Reviewed-by: Niels Weber <niels.weber@theqtcompany.com>

src/plugins/ios/iosdeploystep.h

@@ -88,7 +88,7 @@ private slots:
 private:
     IosDeployStep(ProjectExplorer::BuildStepList *bc,
         IosDeployStep *other);
-    bool init() override;
+    bool init(QList<const BuildStep *> &earlierSteps) override;
     ProjectExplorer::BuildStepConfigWidget *createConfigWidget() override;
     bool immutable() const override { return true; }
     bool runInGuiThread() const override { return true; }