Fix linker err missing boost filesystem library

One needs Boost filesystem library to build armnn.so and GatordMock

Signed-off-by: Ayan Halder <ayan.halder@arm.com>
Change-Id: I108910047fa723e26c87ed6b1e9d401fae3e985e
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 788ce7e..9c2f331 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -602,6 +602,7 @@
 install(DIRECTORY include/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 
 target_link_libraries(armnn ${Boost_THREAD_LIBRARY}
+                            ${Boost_FILESYSTEM_LIBRARY}
                             ${Boost_SYSTEM_LIBRARY})
 
 if(ARMCOMPUTENEON OR ARMCOMPUTECL)
@@ -1091,6 +1092,7 @@
                           timelineDecoder
                           gatordMockService
                           ${Boost_PROGRAM_OPTIONS_LIBRARY}
+                          ${Boost_FILESYSTEM_LIBRARY}
                           ${Boost_SYSTEM_LIBRARY})
 
     if(Threads_FOUND AND (NOT ("${CMAKE_SYSTEM_NAME}" STREQUAL Android)))