There is an updated pull request by fosslinux against master on the void-packages repository

https://github.com/fosslinux/void-packages python-matplotlib-fix
https://github.com/void-linux/void-packages/pull/24988

python-numpy: fix for armv5tel-musl.
musl differs from glibc in that it dosen't provide fenv.h, on arm, when it
believes the architecture dosen't use hardware floating point in any
way. While this is mostly correct, numpy dosen't use them for floating
point reasons -- it just uses them as general, as per the code, "normal
GCC" constants. Hence, extract the constants from the file and provide
them to numpy all the time for armv5tel-musl, the only affected arch.

A patch file from https://github.com/void-linux/void-packages/pull/24988.patch is attached