All my machines are still running Ubuntu 16.04 LTS, there are far too many of them for me to be in any rush to upgrade to Ubuntu 18.
I cannot compile the GUI version of your newfangled GPL2, it seems to be something to do maybe with paths that have "C:" imbedded in the path?
At least those lines are the only ones I can find in the Makefile that mention 1_59 or 1.59, and the error that breaks the compile in the end says
/usr/bin/ld: cannot find -lboost_system-mgw49-mt-s-1_59
/usr/bin/ld: cannot find -lboost_filesystem-mgw49-mt-s-1_59
/usr/bin/ld: cannot find -lboost_program_options-mgw49-mt-s-1_59
/usr/bin/ld: cannot find -lboost_thread-mgw49-mt-s-1_59
collect2: error: ld returned 1 exit status
Makefile:559: recipe for target 'goldpressedlatinum-qt' failed
make: *** [goldpressedlatinum-qt] Error 1
Isn't mgw some kind of tool for cross-compiling FOR WINDOWS on linux machines? If so it looks like the Makefile somehow thinks I am trying to cross-compile for Windows, though I do not know what would give it that idea.
I tried qmake with and without RELEASE=1
I have not yet ever even attempted to compile a GUI for the old GPL, maybe if I tried I would find it has this same problem?
Diamond (DMD) coin has a GUI that compiles just fine, but, they use ./configure system so probably are able to figure out I am trying to compile on Linux for Linux not on Linux for Windows.
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I have compiled GPL2 headless (no-GUI) no problem, and thanks to your foresight in assigning new port numbers I am having no problems so far setting it up right alongside the old version of GPL. I didn't check whether you also changed the default directory, I forced use of ~/.GPL2 in my GPL2start.sh script so I wouldn't have to check. But it occurs to me it could be useful for players to know whether in fact it does have a different default directory from the old versions.
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-MarkM-