Update SingleApplication to upstream master

SingleApplication/examples/calculator/CMakeLists.txt

@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.7.0)
+
+project(calculator LANGUAGES CXX)
+
+set(CMAKE_AUTOMOC ON)
+
+# SingleApplication base class
+set(QAPPLICATION_CLASS QApplication)
+add_subdirectory(../.. SingleApplication)
+
+find_package(Qt${QT_DEFAULT_MAJOR_VERSION} COMPONENTS Core REQUIRED)
+
+add_executable(${PROJECT_NAME}
+    button.h
+    calculator.h
+    button.cpp
+    calculator.cpp
+    main.cpp
+)
+
+target_link_libraries(${PROJECT_NAME} SingleApplication::SingleApplication)