merge: upstream fixes (mutt/default)

 * Add a --disable-doc configuration option.
 * Make ncurses and ncursesw header checking the same.
 * Attempt to silence a clang range warning. (closes #3891)
 * Fixed issue from changeset 4da647a80c55. (closes #3892)
 * Define PATH_MAX, it's missing on the GNU Hurd. (closes #3815)