[C] Fix warning on cnc metadata length.
[C] Fix warning on cnc metadata length.

mikeb01/Aeron,real-logic/Aeron,mikeb01/Aeron,real-logic/Aeron,mikeb01/Aeron,EvilMcJerkface/Aeron,real-logic/Aeron,EvilMcJerkface/Aeron,EvilMcJerkface/Aeron,EvilMcJerkface/Aeron,real-logic/Aeron,mikeb01/Aeron