def: Add a new enum to allow differntiation between sinks and sources.

This is for bits of code or API where the concepts and constructs are
extensibly the same for sinks and sources. To avoid duplication we can
simply define our structure/API and then use this enum to differentiate
the two.

src/pulse/def.h

@@ -124,6 +124,17 @@ typedef enum pa_context_flags {
 #define PA_CONTEXT_NOFAIL PA_CONTEXT_NOFAIL
 /** \endcond */
 
+/** The type of device we are dealing with */
+typedef enum pa_device_type {
+    PA_DEVICE_TYPE_SINK,     /**< Playback device */
+    PA_DEVICE_TYPE_SOURCE    /**< Recording device */
+} pa_device_type_t;
+
+/** \cond fulldocs */
+#define PA_DEVICE_TYPE_SINK PA_DEVICE_TYPE_SINK
+#define PA_DEVICE_TYPE_SOURCE PA_DEVICE_TYPE_SOURCE
+/** \endcond */
+
 /** The direction of a pa_stream object */
 typedef enum pa_stream_direction {
     PA_STREAM_NODIRECTION,   /**< Invalid direction */