Add a virtual destructor to private CacheSet Matcher

This silences the warning:
| warning: ‘class Matcher’ has virtual functions and accessible non-virtual destructor [-Wnon-virtual-dtor]

1 files changed, 1 insertions, 0 deletions

diff --git a/apt-private/private-cacheset.h b/apt-private/private-cacheset.h
index e8dba5a7d..cad8e4a00 100644
--- a/apt-private/private-cacheset.h
+++ b/apt-private/private-cacheset.h
@@ -68,6 +68,7 @@ class Matcher {
 public:
     virtual bool operator () (const pkgCache::PkgIterator &/*P*/) {
         return true;}
+    virtual ~Matcher() = default;
 };
 
 // FIXME: add default argument for OpProgress (or overloaded function)