cmd/compile: include liveness info in GOSSAFUNC output

cmd/compile: include liveness info in GOSSAFUNC output

For this function
```
func test(a, b int, c string, s []int, r [3]int, f ifn) {
	in(a)
	in(b)
	sl(s)
	ar(r)
	fu(f)
}
```
this output
```
HASH live at entry to test: f s
HASH /Users/drchase/work/src/live/main.go
	00000 (15) TEXT main.test(SB), ABIInternal
	00001 (15) FUNCDATA $0, gclocals·vYpXgR4/KsH5nhFsqkHG1Q==(SB)
	00002 (15) FUNCDATA $1, gclocals·Soq6RzO4SX8YA1O9euewoQ==(SB)
	00003 (15) FUNCDATA $5, main.test.arginfo1(SB)
	00004 (15) FUNCDATA $6, main.test.argliveinfo(SB)
b1	00005 (15) PCDATA $3, $1
v32	00006 (21) MOVD R6, main.s+72(RSP)
v27	00007 (21) MOVD R5, main.s+64(RSP)
v30	00008 (21) MOVD R4, main.s+56(RSP)
v7	00009 (21) MOVD R1, main.b+32(RSP)
v34	00010 (21) MOVD R7, main.f+80(RSP)
v34	00011 (21) PCDATA $3, $2
v15	00012 (+16) PCDATA $1, $0
HASH live at call to in: f s
v15	00013 (+16) CALL main.in(SB)
v3	00014 (+17) MOVD main.b+32(RSP), R0
HASH live at call to in: f s
v17	00015 (+17) CALL main.in(SB)
v8	00016 (+18) MOVD main.s+56(RSP), R0
v21	00017 (18) MOVD main.s+64(RSP), R1
v33	00018 (18) MOVD main.s+72(RSP), R2
v19	00019 (+18) PCDATA $1, $1
HASH live at call to sl: f
v19	00020 (+18) CALL main.sl(SB)
v29	00021 (+19) LDP main.r(RSP), (R1, R2)
v9	00022 (19) STP (R1, R2), 8(RSP)
v12	00023 (19) MOVD main.r+16(RSP), R1
v31	00024 (19) MOVD R1, 24(RSP)
HASH live at call to ar: f
v22	00025 (+19) CALL main.ar(SB)
v35	00026 (+20) MOVD main.f+80(RSP), R0
v24	00027 (+20) PCDATA $1, $2
HASH live at call to fu:
v24	00028 (+20) CALL main.fu(SB)
b1	00029 (21) RET
	00030 (?) END
```

Where "HASH" is the git commit comment character I don't know how
to escape and this was easier than fighting with git.

Change-Id: I0691a3f7988db111d11d69388ace83641a841e57
Reviewed-on: https://go-review.googlesource.com/c/go/+/641360
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>