FreeBSD compilation fail (amplmp issue)

[Mizux]

When trying to build SCIP in our Vagrant generic/FreeBSD13 box (note a FreeBSD VirtualBox img) we are facing some compilation issue...

Observed

here the relevant trace (please notice we are building SCIP using FetchContent from our or-tools CMake based build)

default: [ 48%] Building CXX object _deps/scip-build/src/CMakeFiles/libscip.dir/amplmp/src/os.cpp.o
    default: cd /usr/home/vagrant/project/build/_deps/scip-build/src && /usr/bin/c++  -I/usr/home/vagrant/project/build/_deps/scip-src/src/amplmp/include -I/usr/home/vagrant/project/build/_deps/scip-build -I/usr/home/vagrant/project/build/_deps/scip-src/src -I/usr/home/vagrant/project/build/_deps/zlib-build -I/usr/home/vagrant/project/build/_deps/zlib-src -O3 -DNDEBUG -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -std=c++14 -MD -MT _deps/scip-build/src/CMakeFiles/libscip.dir/amplmp/src/os.cpp.o -MF CMakeFiles/libscip.dir/amplmp/src/os.cpp.o.d -o CMakeFiles/libscip.dir/amplmp/src/os.cpp.o -c /usr/home/vagrant/project/build/_deps/scip-src/src/amplmp/src/os.cpp
    default: /usr/home/vagrant/project/build/_deps/scip-src/src/amplmp/src/os.cpp:108:4: error: GetExecutablePath is not implemented for this system
    default: #  error GetExecutablePath is not implemented for this system
    default:    ^
    default: 1 error generated.
    default: *** Error code 1
    default: 
    default: Stop.
    default: make[2]: stopped in /usr/home/vagrant/project/build
    default: *** Error code 1
    default: 
    default: Stop.
    default: make[1]: stopped in /usr/home/vagrant/project/build
    default: *** Error code 1
    default: 
    default: Stop.
    default: make: stopped in /usr/home/vagrant/project/build
The SSH command responded with a non-zero exit status. Vagrant
assumes that this means the command failed. The output for this command
should be in the log above. Please read the output to determine what
went wrong.

ref: https://github.com/google/or-tools/runs/3672547012?check_suite_focus=true

https://github.com/scipopt/scip/blob/9444e80869f6ac42723f3a43712ca6d4ce0c20dc/src/amplmp/src/os.cpp#L107-L109

Expected

Have support of FreeBSD so we can use it in OR-Tools or at least a dummy function instead of this error message breaking the build ;)
Also it seems that amplmp is only use to read some .nl file so it's sad to break the build for this "optional" feature...
https://github.com/scipopt/scip/blob/9444e80869f6ac42723f3a43712ca6d4ce0c20dc/src/amplmp/README#L2

Proposal

2min googling around:
https://fossies.org/linux/sccs/libschily/getexecpath.c seems to be a good starting point to fix amplmp source code

Annexe

Vagrantfile: https://github.com/google/or-tools/blob/master/cmake/vagrant/freebsd/cpp/Vagrantfile

• SCIP issue: Add support for FreeBSD (amplmp compilation issue) scipopt/scip#7
• AMPL/MP issue: