log4cxx: add Qt6 support, drop unused patches, drop pkgconf dep

[valgur]

Summary

Changes to recipe: log4cxx/[*]

Motivation

Allows Qt6 to be used, which also supports cross-compilation.

Details

• Although the project CMake tries to use pkg-config for some deps, all of them are provided as CMake modules by Conan and the recipe does not even call PkgConfigDeps(self).generate() in the first place: https://github.com/search?q=repo%3Aapache%2Flogging-log4cxx%20PkgConfig&type=code
• tool_requires for Qt is not needed.
• Use a version range for expat.
• Drop leftover patch files, which are no longer used.

Logs

Build logs for gcc-13-aarch64-linux-gnu (profile and environment):

• -o with_qt=True: log4cxx-static.log

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• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• Tested locally with at least one configuration using a recent version of Conan