dbus/1.12.20: Use CMake to build D-Bus to fix cross-compiling

[jwillikers]

Currently, Autotools errors out when attempting to cross-compile D-Bus.
However, D-Bus can be built with CMake by defining a simple variable.
Using CMake, D-Bus is able to be cross-compiled successfully.
This minimizes the complexity of the D-Bus Conanfile by using 1 build system.

D-Bus has better support for CMake in newer versions.
This should lead to reduced maintenance overhead in the future, too.

Specify library name and version: dbus/1.12.20

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the conan-center hook activated.

[github-actions]

Hooks produced the following warnings for commit f5501e4

dbus/1.12.20

post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libdbus-1.so' links to system library 'pthread' but it is not in cpp_info.system_libs.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libdbus-1.so' links to system library 'rt' but it is not in cpp_info.system_libs.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library '.\bin\dbus-1-3.dll' links to system library 'iphlpapi' but it is not in cpp_info.system_libs.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library '.\bin\dbus-1-3.dll' links to system library 'ws2_32' but it is not in cpp_info.system_libs.

[jwillikers]

@ericLemanissier PTAL

[prince-chrismc]

One question

[jwillikers]

@tsondergaard I figured out the issue when building on FreeBSD using CMake. As it turns out, there's even an existing commit upstream that fixes the issue. I've pulled that commit as a patch here and it now builds for me on FreeBSD using CMake.

[uilianries]

LGTM

[conan-center-bot]

All green in build 21 (d8c68e7824538d4b58f69f1191d6c7e090c2982e):

• dbus/1.12.20@:
  All packages built successfully! (All logs)

  🔸 Informative: This recipe is not ready for Conan v2

  _{We have started the migration process to Conan v2 and exporting recipes successfully will be required in the future.
  This is just an informative note to gain awareness about the process, no need to take any action. The plan is to enforce smaller steps that are easier to fix and, eventually, this conan export step will work.
  See the recipe migration guide to know more about the changes required.}

  ERROR: Error loading conanfile at '/home/conan/w/prod_cci_PR-11616/recipes/dbus/1.x.x/conanfile.py': Unable to load conanfile in /home/conan/w/prod_cci_PR-11616/recipes/dbus/1.x.x/conanfile.py
    File "<frozen importlib._bootstrap_external>", line 728, in exec_module
    File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
    File "/home/conan/w/prod_cci_PR-11616/recipes/dbus/1.x.x/conanfile.py", line 7, in <module>
      from conans import CMake
  ImportError: cannot import name 'CMake' from 'conans' (/opt/pyenv/versions/3.7.13/lib/python3.7/site-packages/conans/__init__.py)