runtime: main goroutine does not have id 1

[rsc]

CL 117810043 fixes this. I'd like it to be in 1.3.1 so that we can get back to canonical
numbering in goroutine dumps as quickly as possible. I don't want people to have to
remember that 1.3 started numbering at 16 for much longer.

[dvyukov]

Comment 1:

cl 117810043 is submitted

Status changed to Fixed.

[rsc]

Comment 2:

Trivial fix. 
Problem is not critical.
It does make debugging much easier if you can identify the main goroutine, but we are so
far behind on issuing 1.3.1 that the benefit I was going for (people using 1.3 not
seeing goroutine 16 as main goroutine) is no longer achievable.
Delaying to 1.4.

Labels changed: added release-go1.4, removed release-go1.3.1.