VCS: Do not claim to support any operation if unconfigured

Make sure none of the VCS systems claims it does support any
VCS operation while unconfigured. This stops the specific
VCS from showing up in wizards, etc. till they can actually
be used.

src/plugins/cvs/cvscontrol.cpp

@@ -32,6 +32,7 @@
 
 #include "cvscontrol.h"
 #include "cvsplugin.h"
+#include "cvssettings.h"
 
 #include <QtCore/QFileInfo>
 
@@ -48,9 +49,18 @@ QString CVSControl::displayName() const
     return QLatin1String("cvs");
 }
 
+bool CVSControl::isConfigured() const
+{
+    const QString binary = m_plugin->settings().cvsCommand;
+    if (binary.isEmpty())
+        return false;
+    QFileInfo fi(binary);
+    return fi.exists() && fi.isFile() && fi.isExecutable();
+}
+
 bool CVSControl::supportsOperation(Operation operation) const
 {
-    bool rc = true;
+    bool rc = isConfigured();
     switch (operation) {
     case AddOperation:
     case DeleteOperation:

src/plugins/cvs/cvscontrol.h

@@ -50,6 +50,7 @@ public:
 
     bool managesDirectory(const QString &directory, QString *topLevel = 0) const;
 
+    bool isConfigured() const;
     bool supportsOperation(Operation operation) const;
     bool vcsOpen(const QString &fileName);
     bool vcsAdd(const QString &fileName);