add libs' cmakelists file

StgSharp.Native/lib/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.16)
+
+if(NOT DEFINED STGSHARP_NATIVE_EXTERNAL_TARGET)
+  message(FATAL_ERROR "STGSHARP_NATIVE_EXTERNAL_TARGET must be set before adding lib/.")
+endif()
+
+include(${CMAKE_CURRENT_LIST_DIR}/../ExternalLibs.cmake OPTIONAL)
+
+file(GLOB LIB_PACKAGE_DIRS RELATIVE ${CMAKE_CURRENT_LIST_DIR} ${CMAKE_CURRENT_LIST_DIR}/*)
+
+foreach(_pkg ${LIB_PACKAGE_DIRS})
+  set(_pkg_dir ${CMAKE_CURRENT_LIST_DIR}/${_pkg})
+  if(NOT IS_DIRECTORY ${_pkg_dir})
+    continue()
+  endif()
+
+  if(EXISTS ${_pkg_dir}/CMakeLists.txt)
+    add_subdirectory(${_pkg_dir})
+  else()
+    sn_register_external_package(${STGSHARP_NATIVE_EXTERNAL_TARGET} ${_pkg} ${_pkg_dir})
+  endif()
+endforeach()

StgSharp.Native/lib/glfw/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.16)
+
+sn_register_external_package(${STGSHARP_NATIVE_EXTERNAL_TARGET} glfw ${CMAKE_CURRENT_LIST_DIR})
+
+if(WIN32)
+  if(NOT EXISTS ${CMAKE_CURRENT_LIST_DIR}/glfw3_mt.lib)
+    message(FATAL_ERROR "Required GLFW static library not found: ${CMAKE_CURRENT_LIST_DIR}/glfw3_mt.lib")
+  endif()
+
+  sn_link_external_binary_if_exists(${STGSHARP_NATIVE_EXTERNAL_TARGET} ${CMAKE_CURRENT_LIST_DIR}/glfw3_mt.lib)
+endif()

StgSharp.Native/lib/stbi/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.16)
+
+sn_register_external_package(${STGSHARP_NATIVE_EXTERNAL_TARGET} stbi ${CMAKE_CURRENT_LIST_DIR})