libtsffs.so: incompatibility between Simics 6/7

[Wenzel]

Build for Simics 6.0.185
Run Simics 7.70.0

Failed to load module 'tsffs' ('/home/mtarral/simics/simics-tsffs-6.1.7/linux64/lib/libtsffs.so'): "/home/mtarral/simics/simics-tsffs-6.1.7/linux64/lib/libtsffs.so: undefined symbol: VT_save_micro_checkpoint"

Build for Simics 7.70.0
Run Simics 6.0.185

Failed to load module 'tsffs' ('/home/mtarral/simics/simics-6.0.185/../simics-tsffs-6.1.7/linux64/lib/libtsffs.so'): "/home/mtarral/simics/simics-6.0.185/../simics-tsffs-6.1.7/linux64/lib/libtsffs.so: undefined symbol: SIM_take_snapshot, version SIMICS_7000"