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/projectexplorer/abstractprocessstep.cpp

@@ -178,8 +178,9 @@ void AbstractProcessStep::setIgnoreReturnValue(bool b)
     YourBuildStep::init().
 */
 
-bool AbstractProcessStep::init()
+bool AbstractProcessStep::init(QList<const BuildStep *> &earlierSteps)
 {
+    Q_UNUSED(earlierSteps);
     return true;
 }