Linux is missing files when compiled with cmake

[Mangomm]

if (CMAKE_SYSTEM_NAME MATCHES "Linux")
add_definitions(-fPIC)
list(APPEND SOURCES
src/mfx_library_iterator_linux.cpp
src/mfx_load_dll_linux.cpp
src/mfx_critical_section_linux.cpp
)
endif (CMAKE_SYSTEM_NAME MATCHES "Linux")

missing：
CMake Error at 3rdlib/src/libmfx/CMakeLists.txt:70 (add_library):
Cannot find source file:

src/mfx_library_iterator_linux.cpp

CMake Error at 3rdlib/src/libmfx/CMakeLists.txt:70 (add_library):
No SOURCES given to target: libmfx

Since version 1.32.1, these files are missing.