Mac 10.5 CoreText fix.

modules/juce_graphics/native/juce_mac_Fonts.mm

@@ -23,14 +23,20 @@
   ==============================================================================
 */
 
-#if JUCE_IOS || (JUCE_MAC && defined (MAC_OS_X_VERSION_10_5) \
-                  && MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5 \
-                  && MAC_OS_X_VERSION_MAX_ALLOWED > MAC_OS_X_VERSION_10_5)
+#if JUCE_IOS || (JUCE_MAC && MAC_OS_X_VERSION_MIN_REQUIRED > MAC_OS_X_VERSION_10_4)
  #define JUCE_CORETEXT_AVAILABLE 1
 #endif
 
 #if JUCE_CORETEXT_AVAILABLE
 
+#if JUCE_MAC && MAC_OS_X_VERSION_MAX_ALLOWED == MAC_OS_X_VERSION_10_5
+extern "C"
+{
+    void CTRunGetAdvances (CTRunRef, CFRange, CGSize buffer[]);
+    const CGSize* CTRunGetAdvancesPtr (CTRunRef);
+}
+#endif
+
 namespace CoreTextTypeLayout
 {
     static String findBestAvailableStyle (const String& typefaceName, const String& style)