=== Location of libbasix.so ===

The upstream installation of basix places libbasix.so in the lib
subdir of the python module, /usr/lib/python3/dist-packages/basix/lib

However, libbasix.so is not a python extension, it is a "private"
library.  dh_python3 will automatically rename it to
libbasix.cpython-39-<arch>.so, but if that is done then the
python extension _basixcpp.cpython-39-<arch>.so is not able to find
"libbasix.so".

libbasix.so can be left with its own name using "dh_python3 -Xlibbasix.so"
or "dh_python3 --no-ext-rename" instead of renaming with an
arch-specific suffix. In this case the python module will work for a
given arch installation.  But the filepath
/usr/lib/python3/dist-packages/basix/lib/libbasix.so will then
conflict in multiarch installations.

For this reason, libbasix.so has been split out into libbasix-dev and
libbasix0.9 as a conventional public shared library located in the
standard library path /usr/lib/<arch>, and assigned SOVERSION=0.9

For consistency with the shared library, the header file basix.h has
also been installed in libbasix-dev under the standard header path
/usr/include, rather than inside the python module.
