make 6a, 6c, 6g, 6l, libmach_amd64 build on 64-bit gcc.

make 6a, 6c, 6g, 6l, libmach_amd64 build on 64-bit gcc.
these guys really really want long to be 32-bits,
so ,s/long/int32/ (and then manual fixup).
still passes all tests.

(i started out looking for just those longs that
needed to be int32 instead, and it was just too hard
to track them down one by one.)

the longs were rare enough that i don't think
it will cause integration problems.

R=ken
OCL=13787
CL=13789