misc/cstring.h: add b_cstring_make_empty(), cosmetic changes
misc/cstring.h: add b_cstring_make_empty(), cosmetic changes

DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn