check-code: add a rules to catch os.path.abspath
All previous usages have been migrated. So let us add a check-code rules to
catch future usages.
We restrict it to mercurial/ and hgext/ because multiple other script never
depends on Mercurial modules.
Differential Revision: https://phab.mercurial-scm.org/D11072
{
"version": 1,
"project": "mercurial",
"project_url": "https://mercurial-scm.org/",
"repo": "..",
"branches": ["default", "stable"],
"environment_type": "virtualenv",
"show_commit_url": "https://www.mercurial-scm.org/repo/hg/rev/",
"benchmark_dir": "benchmarks",
"env_dir": "../.asv/env",
"results_dir": "../.asv/results",
"html_dir": "../.asv/html"
}