[C++] Use add_compile_options wherever possible.
[C++] Use add_compile_options wherever possible.

add_compile_options works on both C and C++ sources and has a cleaner
usage less prone to wiping off old flags.

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