I then renamed the file, and used tar -xf to extract it...
Here's the output from the session after that...
mike@...123...:~/genode-12.05/build.lx$ make run/demo
/bin/bash: /usr/local/genode-gcc/bin/genode-x86-g++: No such file or directory
dirname: missing operand
Try `dirname --help' for more information.
using run script /home/mike/genode-12.05/base-linux/run/env
using run script /home/mike/genode-12.05/os/run/demo.run
building targets: core init drivers/timer server/nitpicker server/liquid_framebuffer app/launchpad app/scout test/nitpicker server/nitlog drivers/framebuffer drivers/pci drivers/input
spawn make core init drivers/timer server/nitpicker server/liquid_framebuffer app/launchpad app/scout test/nitpicker server/nitlog drivers/framebuffer drivers/pci drivers/input
make[1]: Entering directory `/home/mike/genode-12.05/build.lx'
/bin/bash: /usr/local/genode-gcc/bin/genode-x86-g++: No such file or directory
dirname: missing operand
Try `dirname --help' for more information.
checking library dependencies...
/bin/bash: /usr/local/genode-gcc/bin/genode-x86-g++: No such file or directory
dirname: missing operand
Try `dirname --help' for more information.
/bin/bash: /usr/local/genode-gcc/bin/genode-x86-g++: No such file or directory
dirname: missing operand
Try `dirname --help' for more information.
Skip target drivers/framebuffer/fiasco_ux because it requires fiasco
Skip target drivers/framebuffer/pl11x/pbxa9 because it requires pl11x platform_pbxa9
Skip target drivers/framebuffer/pl11x/vea9x4 because it requires pl11x platform_vea9x4
Skip target drivers/framebuffer/pl11x/vpb926 because it requires pl11x platform_vpb926
Skip target drivers/framebuffer/vesa because it requires vesa
Skip target drivers/input/fiasco_ux because it requires fiasco
Skip target drivers/input/ps2/pl050 because it requires pl050
Skip target drivers/input/ps2/x86 because it requires ps2
Skip target drivers/timer/codezero because it requires codezero
Skip target drivers/timer/fiasco because it requires fiasco
Skip target drivers/timer/foc because it requires foc
Skip target drivers/timer/nova because it requires nova
Skip target drivers/timer/okl4_arm because it requires okl4 arm
Skip target drivers/timer/okl4_x86 because it requires okl4
Skip target drivers/timer/pistachio because it requires pistachio
/bin/bash: /usr/local/genode-gcc/bin/genode-x86-g++: No such file or directory
dirname: missing operand
Try `dirname --help' for more information.
Library platform
MERGE platform.lib.a
/bin/bash: /usr/local/genode-gcc/bin/genode-x86-ar: No such file or directory
make[3]: *** [platform.lib.a] Error 127
make[2]: *** [platform.lib] Error 2
make[1]: *** [gen_deps_and_build_targets] Error 2
make[1]: Leaving directory `/home/mike/genode-12.05/build.lx'
Error: Genode build failed
make: *** [run/demo] Error 252
mike@...123...:~/genode-12.05/build.lx$