For HP-UX, do not potentially deref NULL CopFILESV.

(HP-UX and other ARG_ZERO_IS_SCRIPT platforms)
Do not printf U32 and I32 (both) as %i.

(Detected in HP-UX.)
d_namlen can be signed.

In HP-UX, it is either short or char (which can be either signed or unsigned),
depending on the compiler flags.
Use of the Uid_t_sign and casting instead of Uid_t_f.

HP-UX B.11.31/64 gcc 4.7.2 with -DDEBUGGING:
taint.c:38:2: warning: format '%ld' expects argument of type 'long int', but argument 5 has type 'uid_t' [-Wformat]

This removes the sole use of Uid_t_f (and there are none of Gid_t_f)
from the core.
Disable and document xop_name gcc warning seen in HP-UX.