[nostalgia] Remove unused files

mg.yml

@@ -1,35 +0,0 @@
----
-envs:
-   nostalgia_devenv:
-      dockerfile_path: ./Dockerfile
-cmake:
-   .:
-      src_dir: .
-      build_dir: build/${target}-${build_type}
-      generator: Unix Makefiles
-      defs:
-         CMAKE_EXPORT_COMPILE_COMMANDS: ON
-         CMAKE_INSTALL_PREFIX: dist/${target}-${build_type}
-         CMAKE_INSTALL_RPATH: dist/${target}-${build_type}
-         NOSTALGIA_BUILD_TYPE: OFF
-      build_types:
-         release:
-            defs:
-               CMAKE_BUILD_TYPE: Release
-         debug:
-            defs:
-               USE_ASAN: ON
-               CMAKE_BUILD_TYPE: Debug
-      targets:
-         linux:
-            env: nostalgia_devenv
-         windows:
-            env: nostalgia_devenv
-            defs:
-               CMAKE_TOOLCHAIN_FILE: cmake/modules/Mingw.cmake
-         gba:
-            env: nostalgia_devenv
-            defs:
-               CMAKE_TOOLCHAIN_FILE: cmake/modules/GBA.cmake
-               NOSTALGIA_BUILD_TYPE: GBA
-               OX_USE_STDLIB: OFF