make/info-build: Protect shell from parentheses in CFLAGS
make/info-build: Protect shell from parentheses in CFLAGS

As for why the `-e` is being removed, observe that the `-e` would
otherwise be printed; there is an [elaborate treatise] on what happens
there.

[elaborate treatise]: https://unix.stackexchange.com/questions/700675/why-is-echo-e-behaving-weird-in-a-makefile

RIOT-OS/RIOT,ant9000/RIOT,ant9000/RIOT,kaspar030/RIOT,ant9000/RIOT,miri64/RIOT,jasonatran/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,miri64/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,jasonatran/RIOT,miri64/RIOT,RIOT-OS/RIOT,miri64/RIOT,kaspar030/RIOT,jasonatran/RIOT,ant9000/RIOT,jasonatran/RIOT,kaspar030/RIOT,ant9000/RIOT,miri64/RIOT,RIOT-OS/RIOT