Merge branch 'jk/c23-const-preserving-fixes'

Adjust the codebase for C23 that changes functions like strchr() that discarded constness when they return a pointer into a const string to preserve constness. * jk/c23-const-preserving-fixes: config: store allocated string in non-const pointer rev-parse: avoid writing to const string for parent marks revision: avoid writing to const string for parent marks rev-parse: simplify dotdot parsing revision: make handle_dotdot() interface less confusing