[dev.cc] runtime: change set_sec to take int64

Fixes build.
Tested that all these systems can make.bash.

TBR=austin
CC=golang-codereviews
https://codereview.appspot.com/177770043
[dev.cc] liblink: fix warnings on Plan 9

warning: src/liblink/asm9.c:501 set and not used: bflag
warning: src/liblink/list9.c:259 format mismatch .5lux INT, arg 4
warning: src/liblink/list9.c:261 format mismatch .5lux INT, arg 3
warning: src/liblink/list9.c:319 more arguments than format VLONG
warning: src/liblink/obj9.c:222 set and not used: autoffset

LGTM=bradfitz, austin
R=rsc, bradfitz
CC=austin, golang-codereviews
https://codereview.appspot.com/175070043
[dev.cc] runtime: fix bus error accessing auxv random data on arm5

It's rather unsporting of the kernel to give us a pointer to unaligned memory.

This fixes one crash, the next crash occurs in the soft float emulation.

LGTM=minux, rsc, austin
R=minux, rsc, austin
CC=golang-codereviews
https://codereview.appspot.com/177730043
[dev.cc] runtime: fix _sfloat thunk

* _sfloat dispatches to runtime._sfloat2 with the Go calling convention, so the seecond argument is a [15]uint32, not a *[15]uint32.
* adjust _sfloat2 to return the new pc in 68(R13) as expected.

LGTM=rsc
R=minux, austin, rsc
CC=golang-codereviews
https://codereview.appspot.com/174160043
[dev.garbage] all: merge dev.cc (723ca3789b88) into dev.garbage

Brings in Linux time signature fixes. Should fix build.

TBR=austin
CC=golang-codereviews
https://codereview.appspot.com/176870043