[C/C++] Fix Travis build script of GCC 8.
[C/C++] Fix Travis build script of GCC 8.

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