Fix builtin variable names

mesonbuild/ast/introspection.py

mesonbuild/backend/ninjabackend.py

mesonbuild/compilers/cs.py

mesonbuild/dependencies/ui.py

mesonbuild/mesonlib.py

mesonbuild/mesonmain.py

mesonbuild/minstall.py

mesonbuild/mlog.py

mesonbuild/modules/python.py

mesonbuild/modules/windows.py

mesonbuild/munstable_coredata.py

run_unittests.py

setup.cfg

sideci.yml