[AutotoolsToolchain] Added self.xxxx_options

[franramirez688]

Changelog: Feature: Added new attributes (Python dict) to AutotoolsToolchain: self.configure_options, self.autoreconf_options, and self.make_options.
Changelog: Feature: Added new attribute AutotoolsToolchain.use_new_options (boolean) to keep backward compatibility.
Changelog: Feature: AutotoolsToolchain.xxxxx_args are adequately initialized.
Changelog: Bugfix: AutotoolsToolchain.configure_args was overwriting Conan's pre-calculated arguments.
Docs: https://github.com/conan-io/docs/pull/XXXX
Closes: #12431
Closes: #12642
Closes: #12705
Closes: #12546

Summary:

• Deprecating AutotoolsToolchain.xxxx_args attributes (lists) in favor of AutotoolsToolchain.xxxxx_options ones (dicts).
• Keeping backward compatibility thanks to AutotoolsToolchain.use_new_options (bool) attr. Notice that it should disappear in the future when xxxx_args won't be used.

[SpaceIm]

I think it breaks existing conan-center recipes which have to replace --host & --build by another value. Having to call something like configure_args.remove("--build=x86_64-linux-gnu") to remove --build option is too tedious and error prone, and it means that consumers have to know how autotools toolchain populates these options.

[SpaceIm]

FYI, in conan-center there are currently several recipes migrated to AutotoolsToolchain which are relying on implicit removal of --build/--host options (because there is no build/host/target argument in AutotoolsToolchain like there was in AutotoolsBuildEnvironment) when there are manually injected into tc.configure_args:

• autoconf
• icu
• libcurl
• libffi
• libgettext
• libiconv

It's worth noting that most of these recipes have to replace --build/--host because gnu_triplet is just wrong for Visual Studio.

[memsharded]

It is not fully clear why the new approach do not replace the previous one, and there are smart conversions between the two of them.

[franramirez688]

Superseded by #12884 (less risky approach).