ProjectExplorer: Base IDevice::osType on a data member

Change-Id: I969563e6e62895a51fb4692c8eb0bab278f0ecae
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/webassembly/webassemblydevice.h

@@ -39,8 +39,6 @@ class WebAssemblyDevice : public ProjectExplorer::DesktopDevice
 public:
     static ProjectExplorer::IDevice::Ptr create();
 
-    Utils::OsType osType() const override;
-
 private:
     WebAssemblyDevice();
 };