Once these changes are effected, it is possible to construct
"8l" native on a (386?) Plan 9 system, albeit with assistance
from modules such as mkfiles that are not (yet) included in any
public patches.

8l/asm.c:
. Corrected some format qualifiers.

8l/list.c:
. Cast a print() argument to (int) to match the given format.
  It may be possible to change the format (%R), but I have not
  looked into it.

8l/obj.c:
. Removed some unused code.

8l/span.c:
. Removed unnecessary incrementation on "bp".
. Corrected some format qualifiers.

ld/data.c:
. Corrected some format qualifiers.
. Cast print argument to (int): used as field size.
. Use braces to suppress warning about empty if() statements.

ld/dwarf.c:
. Trivial spelling mistake in comment.

ld/ldelf.c:
. Added USED() statements to silence warnings.
. Dropped redundant address (&) operators.
. corrected some format qualifiers.
. Cast to (int) for switch selection variable.

ld/macho.c:
. Added USED() statements to silence warnings.

ld/ldpe.c:
. Added USED() statements to silence warnings.
. More careful use of "sect" variable.
. Corrected some format qualifiers.
. Removed redundant assignments.
. Minor fix dropped as it was submitted separately.

ld/pe.c:
. Dropped <time.h> which is now in <u.h>.
. Dropped redundant address (&) operators.
. Added a missing variable initialisation.

ld/symtab.c:
. Added USED() statements to silence warnings.
. Removed redundant incrementation.
. Corrected some format qualifiers.

All the above have been tested against a (very) recent release
and do not seem to trigger any regressions.

All review suggestions have been incorporated.

R=rsc
CC=golang-dev
https://golang.org/cl/4633043