package/xz without shared libraries breaks Python build

The new CMake-based build disables shared libraries without any options in package/xz. Unfortunately the host Python 3.12 build then tries to link against the resulting liblzma.a and fails, setting -DBUILD_SHARED_LIBS=ON in package/xz/xz.mk instead fixes the issue.

I'm happy to prepare a patch, but I suspect unconditionally enabling the shared libraries (for host and target, no less) would be considered undesirable to keep builds without Python smaller. What would be the desired behavior here? Check if Python is enabled and enable shared libraries in that case? Or add a config option and have Python select it? To get my build working I've applied the -DBUILD_SHARED_LIBS=ON unconditionally, but I assume target Python is affected too, so a good solution should cover both. 🤔