Statically link libpython on MacOS

[geofft]

In #604 we rolled back ./configure --enable-static-libpython-for-interpreter for macOS because it caused link failures with, it seems, symbols for third-party libraries statically linked into libpython, e.g.:

cpython-3.14> ld64.lld: error: undefined symbol: BZ2_bzDecompress
cpython-3.14> ld64.lld: error: undefined symbol: ffi_prep_closure_loc
cpython-3.14> ld64.lld: error: undefined symbol: Tcl_FindExecutable

The patch also failed on Python 3.9 through 3.11 because it conflicted with this other patch:

# Also on macOS, the `python` executable is linked against libraries defined by statically
# linked modules. But those libraries should only get linked into libpython, not the
# executable. This behavior is kinda suspect on all platforms, as it could be adding
# library dependencies that shouldn't need to be there.
if [[ "${PYBUILD_PLATFORM}" = macos* ]]; then
    if [ "${PYTHON_MAJMIN_VERSION}" = "3.9" ]; then
        patch -p1 -i ${ROOT}/patch-python-link-modules-3.9.patch
    elif [ "${PYTHON_MAJMIN_VERSION}" = "3.10" ]; then
        patch -p1 -i ${ROOT}/patch-python-link-modules-3.10.patch
    else
        patch -p1 -i ${ROOT}/patch-python-link-modules-3.11.patch
    fi
fi

That comment seems extremely relevant to the link failures.

We should turn --enable-static-libpython-for-interpreter back on for macOS builds, and I should understand exactly what that comment means, including investigating whether it makes sense on other platforms.