[C++] Call constructor of LogBuffersDefn explicitly when adding to map. Issue #799.
[C++] Call constructor of LogBuffersDefn explicitly when adding to map. Issue #799.

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