xeus-gp FTBFS on Alpine Linux (musl libc)

[Matthias Koeppe <mkoeppe@ucdavis.edu>]

[xeus_gp-0.1.0] [spkg-install] [1/4] Building CXX object
CMakeFiles/xeus-gp.dir/src/main.cpp.o
[xeus_gp-0.1.0] [spkg-install] FAILED: [code=1]
CMakeFiles/xeus-gp.dir/src/main.cpp.o
[xeus_gp-0.1.0] [spkg-install]
/host/sage-musllinux_1_2_aarch64/libexec/ccache/g++ -std=gnu++11
-DGUID_LIBUUID -DXEUS_GP_EXPORTS
-I/host/sage-musllinux_1_2_aarch64/var/tmp/sage/build/xeus_gp-0.1.0/src/include
-isystem /host/sage-musllinux_1_2_aarch64/include -g -O2
-Wunused-parameter -Wextra -Wreorder -std=c++17 -std=gnu++17
-Wunused-parameter -Wextra -Wreorder -MD -MT
CMakeFiles/xeus-gp.dir/src/main.cpp.o -MF
CMakeFiles/xeus-gp.dir/src/main.cpp.o.d -o
CMakeFiles/xeus-gp.dir/src/main.cpp.o -c
/host/sage-musllinux_1_2_aarch64/var/tmp/sage/build/xeus_gp-0.1.0/src/src/main.cpp
[xeus_gp-0.1.0] [spkg-install]
/host/sage-musllinux_1_2_aarch64/var/tmp/sage/build/xeus_gp-0.1.0/src/src/main.cpp:22:10:
fatal error: execinfo.h: No such file or directory
[xeus_gp-0.1.0] [spkg-install] 22 | #include <execinfo.h>
[xeus_gp-0.1.0] [spkg-install] | ^~~~~~~~~~~~
[xeus_gp-0.1.0] [spkg-install] compilation terminated.
[xeus_gp-0.1.0] [spkg-install] [2/4] Building CXX object
CMakeFiles/xeus-gp-static.dir/src/xinterpreter.cpp.o
[xeus_gp-0.1.0] [spkg-install] ninja: build stopped: subcommand failed.

https://github.com/passagemath/passagemath/actions/runs/16786147027/job/47537672270?pr=1393#step:13:3147
https://github.com/passagemath/passagemath/pull/1393

I can provide a portability CI to run on GitHub Actions if there's interest.

Matthias
-- 
Matthias Koeppe -- http://www.math.ucdavis.edu/~mkoeppe