Improve Mac wx3.1.1 compatibility

1. Qualify hash as std::hash.
2. Ensure we have a header for the function 'free'

lib-src/FileDialog/mac/FileDialogPrivate.mm

@@ -49,6 +49,8 @@
 // implementation
 // ============================================================================
 
+#define NSObject wxOSX_10_6_AND_LATER( x ) x
+
 @interface OSPanelDelegate : NSObject wxOSX_10_6_AND_LATER(<NSOpenSavePanelDelegate>)
 {
     FileDialog* _dialog;

src/MemoryX.h

@@ -3,6 +3,7 @@
 
 // C++ standard header <memory> with a few extensions
 #include <memory>
+#include <cstdlib> // Needed for free.
 #ifndef safenew
 #define safenew new
 #endif

src/commands/CommandManager.h

@@ -103,7 +103,6 @@ namespace std
 #ifdef __AUDACITY_OLD_STD__
    namespace tr1
    {
-#endif
       template<typename T> struct hash;
       template<> struct hash< NormalizedKeyString > {
          size_t operator () (const NormalizedKeyString &str) const // noexcept
@@ -113,8 +112,17 @@ namespace std
             return Hasher{}( stdstr );
          }
       };
-#ifdef __AUDACITY_OLD_STD__
    }
+#else
+   // in std, not in tr1.
+   template<> struct hash< NormalizedKeyString > {
+      size_t operator () (const NormalizedKeyString &str) const // noexcept
+      {
+         auto &stdstr = str.Raw(); // no allocations, a cheap fetch
+         using Hasher = std::hash< wxString >;
+         return Hasher{}( stdstr );
+      }
+   };
 #endif
 }
 

src/import/ImportQT.cpp

@@ -31,6 +31,10 @@ static const wxChar *exts[] =
    wxT("mp4")
 };
 
+#if defined(__WXMAC__)
+#undef USE_QUICKTIME
+#endif
+
 #ifndef USE_QUICKTIME
 
 void GetQTImportPlugin(ImportPluginList &importPluginList,