We were calling AC_CANONICAL_TARGET in configure.ac under the mistaken impression that this allowed setting the target architecture for cross-compilation output.
However, in GNU terminology the system type that this the target of cross-compilation is the "host" and "target" is reserved for setting what the output of the compiled application should itself target, when compiling a cross-compiler. Finally "build" is the system type the build system is itself running under.
So to cross-compile, one invokes
./configure --host ...
In any case, we only make use of the
so that is the macro we need to invoke to provide it.
Thanks to Maarten Bosmans for reporting the issue.