Revert to 'add_definitions()' for '-std=c99' for cgreen-runner
Revert to 'add_definitions()' for '-std=c99' for cgreen-runner

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