misc/cstring.h: add b_cstring_equals_buffer() and b_cstring_memchr()
misc/cstring.h: add b_cstring_equals_buffer() and b_cstring_memchr()

SeReRPRo/badvpn,SeReRPRo/badvpn,SeReRPRo/badvpn,SeReRPRo/badvpn,SeReRPRo/badvpn