ProjectExplorer: Introduce an Targer::activeBuildKey()

... redirecting to activeRunConfiguration()->buildKey()

This will allow the user code side to be moved closer to a setup
that will allow to shift the build data stored in project nodes
to the build system.

Change-Id: Icdf03e77bf61ee03b3a16855ac67652c205402fa
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/projectexplorer/target.cpp

@@ -238,6 +238,15 @@ BuildTargetInfo Target::buildTarget(const QString &buildKey) const
     return buildSystem()->buildTarget(buildKey);
 }
 
+QString Target::activeBuildKey() const
+{
+    // Should not happen. If it does, return a buildKey that wont be found in
+    // the project tree, so that the project()->findNodeForBuildKey(buildKey)
+    // returns null.
+    QTC_ASSERT(d->m_activeRunConfiguration, return QString(QChar(0)));
+    return d->m_activeRunConfiguration->buildKey();
+}
+
 Core::Id Target::id() const
 {
     return d->m_kit->id();

src/plugins/projectexplorer/target.h

@@ -123,6 +123,8 @@ public:
     DeploymentData buildSystemDeploymentData() const;
     BuildTargetInfo buildTarget(const QString &buildKey) const;
 
+    QString activeBuildKey() const; // Build key of active run configuaration
+
 signals:
     void targetEnabled(bool);
     void iconChanged();