Need a fallback for target_link_options due to too old CMake version

Author: TheAssassin

src/build-runtime.cmake

@@ -110,7 +110,11 @@ add_executable(runtime ${CMAKE_CURRENT_BINARY_DIR}/runtime.4.o notify.c)
 # CMake gets confused by the .o object, therefore we need to tell it that it shall link everything using the C compiler
 set_property(TARGET runtime PROPERTY LINKER_LANGUAGE C)
 target_link_libraries(runtime PRIVATE libsquashfuse dl xz libzlib pthread libappimage_shared libappimage_hashlib)
-target_link_options(runtime PRIVATE ${runtime_ldflags})
+if(COMMAND target_link_options)
+    target_link_options(runtime PRIVATE ${runtime_ldflags})
+else()
+    set_property(TARGET runtime PROPERTY LINK_FLAGS ${runtime_ldflags})
+endif()
 target_include_directories(runtime PRIVATE ${PROJECT_SOURCE_DIR}/include)
 
 if(BUILD_DEBUG)