Add WASAPI audio capture

- Add WASAPI audio capture for windows, input and output

 - Check for null pointer in os_dlopen

 - Add exception-safe 'WinHandle' and 'CoTaskMemPtr' helper classes that
   will automatically call CloseHandle on handles and call CoTaskMemFree
   on certain types of memory returned from windows functions

 - Changed the wide <-> MBS/UTF8 conversion functions so that you use
   buffers (like these functions are *supposed* to behave), and changed
   the ones that allocate to a different naming scheme to be safe

libobs-d3d11/d3d11-subsystem.cpp

@@ -170,7 +170,7 @@ void gs_device::InitDevice(gs_init_data *data, IDXGIAdapter *adapter)
 		L"<unknown>";
 
 	char *adapterNameUTF8;
-	os_wcs_to_utf8(adapterName.c_str(), 0, &adapterNameUTF8);
+	os_wcs_to_utf8_ptr(adapterName.c_str(), 0, &adapterNameUTF8);
 	blog(LOG_INFO, "Loading up D3D11 on adapter %s", adapterNameUTF8);
 	bfree(adapterNameUTF8);