Fix unnamed lock in example code (mr !487)

Unnamed lockguards don't actually lock and don't produce warnings.

(cherry picked from commit 87e26f8c)

e899da79 Fix unnamed lock

added 22 commits

• a2935d67...2fd25b6f - 17 commits from branch v29-patches
• fe55e97e - GaudiAlg FunctionalDetails apply range size check in debug builds only (mr !529 (merged))
• 03f32eb5 - GaudiAlg FunctionalDetails apply range size check in debug builds only (mr !556 (merged))
• 2bda8835 - Remove IssueSeverity support from StatusCode (mr !477 (merged))
• 0fe7ba93 - Remove IssueSeverity support from StatusCode (mr !557 (merged))
• 5932bf2f - Fix unnamed lock in example code (mr !487 (merged))

Compare with previous version

mentioned in commit 6cf7c619

merged