ProjectExplorer: Add a BuildConfiguration::regenerateBuildFiles

That's effectively a generic hook for "re-run qmake" without the
qmake/QmakeProjectManager dependency.

Change-Id: I236d40690cde9047831422b2651ed2284b220959
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/projectexplorer/buildconfiguration.cpp

@@ -271,6 +271,12 @@ QString BuildConfiguration::disabledReason() const
     return QString();
 }
 
+bool BuildConfiguration::regenerateBuildFiles(Node *node)
+{
+    Q_UNUSED(node);
+    return false;
+}
+
 QString BuildConfiguration::buildTypeName(BuildConfiguration::BuildType type)
 {
     switch (type) {