Make code compile with Clang on Mac

Change-Id: I70f4f54fefd37fe04adc1789ec31ac4024d0e8cf
diff --git a/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp b/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp
index 2abf08c..0fdb9a5 100644
--- a/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp
+++ b/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp
@@ -619,7 +619,7 @@
                 // get the channel name
                 char *channelName;
                 CFStringRef cfname = NULL;
-                const AudioObjectPropertyAddress address = {kAudioObjectPropertyElementName, port->scope, ch};
+                const AudioObjectPropertyAddress address = {kAudioObjectPropertyElementName, port->scope, static_cast<AudioObjectPropertyElement>(ch)};  // compiles with Clang
                 UInt32 size = sizeof(cfname);
                 OSStatus err = AudioObjectGetPropertyData(mixer->deviceID, &address, 0, NULL, &size, &cfname);
                 if (err == noErr) {