cgen: fix the saving of g.skip_stmt_pos and g.stmt_path_pos when generating anonymous fns (fix #26498)

[spytheman]

Fix #26498 .

Note: I used codex to fix the issue and to make the minimal reproduction.

The prompts I used with gpt-5.2-codex:

• fix v echobot.v . Do not change the file, change /opt/v/vlib/v/gen/c/ . Read the /opt/v/AGENTS.md file .
• add a fix_issue_26498_test.v for that change too in /opt/v/vlib/v/tests/
• The fix is correct, but the test passes with ./v vlib/v/tests/fix_issue_26498_test.v. It should fail with the unmodified compiler. It should work with the new one, when run like this:./vnew vlib/v/tests/
  fix_issue_26498_test.v . Ajdust the test, until it exhibits the same symptoms as the original code.