log: define default virtual destructor for LogHandler

Fixes: https://github.com/Nitrokey/libnitrokey/issues/129
Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/libnitrokey/log.h b/libnitrokey/log.h
index 2a64bef..278b49c 100644
--- a/libnitrokey/log.h
+++ b/libnitrokey/log.h
@@ -46,6 +46,7 @@ namespace nitrokey {
     class LogHandler {
     public:
       virtual void print(const std::string &, Loglevel lvl) = 0;
+      virtual ~LogHandler() = default;
     protected:
       std::string loglevel_to_str(Loglevel);
       std::string format_message_to_string(const std::string &str, const Loglevel &lvl);