Ah, taking it a closer look it appears you are using Xilinx tools. /home/tools/xilinx/SDK/2015.1/bin/unwrapped/lnx64.o/tclsh8.5 suggests that you are using a shell that sourced settings64.sh from Vivado. This script changes LD_LIBRARY_PATH and PATH and may be causing your problems.
Can you try running in a fresh shell without sourcing the Xilinx setup scripts?
After I installed the libtcl package (sudo apt-get install libtcl8.5), the issue is resolved. So maybe add this to the documentation as one of the package requirements? Thanks.