Explicitly define AmbDecConf's destructor

GCC complains it can't inline the destructor because it's "unlikely" to be
called and would bloat code size, despite being implicitly defined. Technically
accurate, but rather annoying since it's not explicitly called or defined.

core/ambdec.cpp

@@ -179,6 +179,9 @@ al::optional<std::string> load_ambdec_matrix(float (&gains)[MaxAmbiOrder+1],
 
 } // namespace
 
+AmbDecConf::~AmbDecConf() = default;
+
+
 al::optional<std::string> AmbDecConf::load(const char *fname) noexcept
 {
     al::ifstream f{fname};

core/ambdec.h

@@ -46,6 +46,8 @@ struct AmbDecConf {
     float HFOrderGain[MaxAmbiOrder+1]{};
     CoeffArray *HFMatrix;
 
+    ~AmbDecConf();
+
     al::optional<std::string> load(const char *fname) noexcept;
 };