fix build on linux (stop propagating unwanted flags from game networking sockets)

Author: malytomas

externals/gamenetworkingsockets/CMakeLists.txt

@@ -37,3 +37,9 @@ set_source_files_properties(
 	TARGET_DIRECTORY GameNetworkingSockets_s
 	PROPERTIES COMPILE_DEFINITIONS "WIN32_LEAN_AND_MEAN;VC_EXTRALEAN;NOMINMAX"
 )
+
+# avoid propagating unwanted flags
+add_library(GameNetworkingSockets STATIC dummy.cpp)
+target_link_libraries(GameNetworkingSockets PRIVATE GameNetworkingSockets_s)
+target_include_directories(GameNetworkingSockets INTERFACE $<TARGET_PROPERTY:GameNetworkingSockets_s,INTERFACE_INCLUDE_DIRECTORIES>)
+add_library(GameNetworkingSockets::GameNetworkingSockets ALIAS GameNetworkingSockets)

externals/gamenetworkingsockets/dummy.cpp

@@ -0,0 +1,4 @@
+void gamenetworkingsockets_dummy_unused_symbol_to_force_cpp_compilation()
+{
+	// do nothing
+}

sources/CMakeLists.txt

@@ -12,7 +12,7 @@ target_compile_features(cage-core PUBLIC cxx_std_${CMAKE_CXX_STANDARD})
 target_include_directories(cage-core PUBLIC $<INSTALL_INTERFACE:include> $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>)
 target_link_libraries(cage-core PRIVATE zlib libzstd_static simplefilewatcher fastnoise hsluv png_static cage-jpeg tiff tiffxx tinyexr stb xatlas pmp dualmc dr_libs ogg vorbis vorbisfile vorbisenc samplerate assimp bc7enc_rdo avir quickhull iwasm_static uni-algo cpr)
 if (cage_use_steam_sockets)
-	target_link_libraries(cage-core PRIVATE GameNetworkingSockets_s)
+	target_link_libraries(cage-core PRIVATE GameNetworkingSockets::GameNetworkingSockets)
 	target_compile_definitions(cage-core PUBLIC "CAGE_USE_STEAM_SOCKETS")
 endif()
 target_link_libraries(cage-core PUBLIC unordered_dense plf)