work around Linux futex implementation

Index: AI/Skirmish/CircuitAI/CMakeLists.txt
--- AI/Skirmish/CircuitAI/CMakeLists.txt.orig
+++ AI/Skirmish/CircuitAI/CMakeLists.txt
@@ -9,7 +9,7 @@ if (WIN32)  # spring::condition_variable_any requireme
 elseif (APPLE)
 	set(additionalSources  ${additionalSources} ${CMAKE_SOURCE_DIR}/rts/System/Platform/Mac/Signal.cpp)
 else ()
-	set(additionalSources  ${additionalSources} ${CMAKE_SOURCE_DIR}/rts/System/Platform/Linux/Futex.cpp)
+	#set(additionalSources  ${additionalSources} ${CMAKE_SOURCE_DIR}/rts/System/Platform/Linux/Futex.cpp)
 endif ()
 set(additionalLibraries    ${Cpp_AIWRAPPER_TARGET} CUtils)
 #set(additionalLibraries    ${Cpp_AIWRAPPER_TARGET} CUtils ${SDL2_LIBRARY})
