Update the .cython_version format to include all cythonize options

[embray]

As discussed beginning here, the current .cython_version stamp does not always accurately reflect all Cython build options which, if changed, should trigger a rebuild of Cython sources.

It would be good to have a more detailed .cython_version that includes all arguments to cythonize() and perhaps all Cython.Compiler.Options.

Although the values of these options are generally simple types, the compiler_directives dict alone makes this data structure complicated enough that an ad hoc format like the one currently used is not justified--instead a json-formatted file should work.

Component: build

Author: Jeroen Demeyer

Branch/Commit: b56b4be

Reviewer: Erik Bray

Issue created by migration from https://trac.sagemath.org/ticket/21843

[jdemeyer]

Branch: u/jdemeyer/update_the__cython_version_format_to_include_all_cythonize_options

[jdemeyer]

New commits:

b56b4be

Include Cython directives in .cython_version file

[jdemeyer]

Author: Jeroen Demeyer

[jdemeyer]

Commit: b56b4be

[embray]

comment:4

Thanks--straightforward enough.

[tscrim]

comment:6

cough cough

[tscrim]

Reviewer: Erik Bray

[vbraun]

Changed branch from u/jdemeyer/update_the__cython_version_format_to_include_all_cythonize_options to b56b4be