The wheelhouse build stage still compiled cmake from PyPI source (pillow ->
pybind11 -> cmake bootstrap, exit 11) after the Dockerfile and the apt install
began upgrading libc++ to 30. LD_LIBRARY_PATH put the payload's pinned libc++ 29
first, and a library found there beats the binary's own RUNPATH, so apt's cmake
died with 'cannot locate symbol _ZNSt6__ndk113__hash_memoryEPKvm' and
scikit-build-core read that as 'no cmake'.
Probed in the pinned termux-docker image under qemu with the same apt package
list: payload libc++ 29 first fails, a one-symlink dir to the system libc++ in
front of it starts cmake and clang. The build now makes that dir after apt runs
and fails fast if cmake cannot start, instead of burning 30 minutes compiling
cpython, cryptography and pillow first.
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