remove context from the devices list of context on context destroy

src/java/org/lwjgl/openal/ALC10.java

@@ -359,6 +359,8 @@ public final class ALC10 {
 		synchronized(ALC10.contexts) {
 			nalcDestroyContext(getContext(context));
 			context.setInvalid();
+			ALCdevice device = alcGetContextsDevice(context);
+			device.removeContext(context);
 		}
 	}
 	native static void nalcDestroyContext(long context);

src/java/org/lwjgl/openal/ALCdevice.java

@@ -89,6 +89,17 @@ public final class ALCdevice {
 			contexts.put(new Long(context.context), context);
 		}
 	}
+	
+	/**
+	 * Remove context associated with device
+	 * 
+	 * @param context Context to disassociate with device
+	 */
+	void removeContext(ALCcontext context) {
+		synchronized (contexts) {
+			contexts.remove(new Long(context.context));
+		}		
+	}	
 
 	/**
 	 * Marks this device and all of its contexts invalid