Improve wasapi backend UWP support (#853)

* Improve wasapi, support uwp build

* Fix compile errors

* [UWP] Support ReadALConfig from app roaming

* [UWP] Post disconnect event when default device changed

* [UWP] Fix appveyor ci

* [WIN32] Default device change notification support

* Fix warnings

* Add event to notify the app when the default device changes

- Event type: AL_EVENT_TYPE_DEFAULT_DEVICE_CHANGED_SOFT=0x19A7
- Event callback parameters:
  void _onALSoftEvent(ALenum eventType,
                    ALuint object, // dataFlow: 0(render), 1(capture)
                    ALuint param, // 0
                    ALsizei length, // 0
                    const ALchar* message, // Default device changed:<deviceId>
                    void* userParam);

* Fix warnings

* Fire default device changed event in mixerProc thread

* Fix compile warning

* [UWP] Improve cmake

* Revert changes

* Notify default device change by system event callback

* Revert insignificant change

* Remove duplicate call

1 files changed, 3 insertions, 0 deletions

diff --git a/config.h.in b/config.h.in
index 477d8c77..d1cf0395 100644
--- a/config.h.in
+++ b/config.h.in
@@ -117,3 +117,6 @@
 
 /* Define the installation data directory */
 #cmakedefine ALSOFT_INSTALL_DATADIR "@ALSOFT_INSTALL_DATADIR@"
+
+/* Define whether build alsoft for winuwp */
+#cmakedefine ALSOFT_UWP