MFC r309392, r309393

r309392:
String terminators are called NUL, not NULL, also the variable
mentioned in the comment is p and not u.

Obtained from: OpenBSD (r1.34)

r309393:
Use memset(3) instead of bzero(3).

Obtained from: OpenBSD (r1.12, r1.20, r1.18 and r1.37)