Add optimizing flag to avoid warning for FORTIFY_SOURCE from gcc 6.2
Add optimizing flag to avoid warning for FORTIFY_SOURCE from gcc 6.2

cgreen-devs/cgreen,thoni56/cgreen,cgreen-devs/cgreen,thoni56/cgreen,cgreen-devs/cgreen,cgreen-devs/cgreen,cgreen-devs/cgreen,thoni56/cgreen,thoni56/cgreen,thoni56/cgreen