ld/data.c:
. Format specifier with corresponding cast to cater for all
  architectures (llux and vlong).

ld/ldelf.c:
ld/ldmacho.c:
. Missing "pn" argument in diag() calls.

ld/ldpe.c:
. Dropped "sym->sectnum" in diag() call.
. Typo in a comment.

ld/lib.h:
. Added varargck pragma for "O".

R=rsc
CC=golang-dev
https://golang.org/cl/4749042