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, 8 insertions, 2 deletions

diff --git a/alc/alconfig.cpp b/alc/alconfig.cpp
index 56cad9e0..3c9a9777 100644
--- a/alc/alconfig.cpp
+++ b/alc/alconfig.cpp
@@ -329,9 +329,14 @@ const char *GetConfigValue(const char *devName, const char *blockName, const cha
 #ifdef _WIN32
 void ReadALConfig()
 {
-    WCHAR buffer[MAX_PATH];
-    if(SHGetSpecialFolderPathW(nullptr, buffer, CSIDL_APPDATA, FALSE) != FALSE)
     {
+#if !defined(ALSOFT_UWP)
+        WCHAR buffer[MAX_PATH];
+        if (!SHGetSpecialFolderPathW(nullptr, buffer, CSIDL_APPDATA, FALSE))
+            return;
+#else
+        auto buffer = Windows::Storage::ApplicationData::Current->RoamingFolder->Path->Data();
+#endif
         std::string filepath{wstr_to_utf8(buffer)};
         filepath += "\\alsoft.ini";
 
@@ -341,6 +346,7 @@ void ReadALConfig()
             LoadConfigFromFile(f);
     }
 
+
     std::string ppath{GetProcBinary().path};
     if(!ppath.empty())
     {