libidn2's use of gentr46map does not support cross compilation.
EDIT: Per conversation below, I mistook the output of make happening right after ./configure finished for the output of ./configure due to a series of similar issues I had seen in other projects.
I would like to request that features not be detected by attempting to run code. Information acquired this way would be better obtained from either the user or utilities in the environment responsible for passing such information to running programs.
I ask you seriously consider this suggestion as any potential changes to the configuration script are not supported by the libidn2 project users will be responsible for them.
Libidn2 is one of many programs or libraries which have configuration scripts which behave in this manner. If you read this report please consider avoiding such things in the future for other projects you may be involved with. Having to self-host on lower end hardware is a major hurdle to running up-to-date (and secure) GNU/Linux systems. Thanks!
Attached is attempted build output. There are lines related to the package manager in use, but hopefully the error is clear enough: