Ensure it compiles when we don't have TCP_ACCOUNTING on

fix stray space

Almost forgot, when going through the compressed ack path we will need to possibly nuke the flag too if
output did not occur...

Opps lets get the sets of the log union in the right place.

In D39501#900051, @tuexen wrote:

Would be nice to know what the problem is you are experiencing with the DSCP for IPv6.

Address Richard and Michaels comments by letting sleeping dogs lie :)

Update comments and spacing per cc's request. I do not update padding since the set of rack
changes is *not* intended to ever be MFC'd.

One missed peak_rate removal ...

Fix another niggle from Gleb, after we seen *ptr == NULL we don't need to set
*ptr to NULL.

Fix rack_init() bug Gleb found, We need to look at *ptr not ptr in our null check

Opps missed one sysctl change that has to be in.

Its in Freebsd now..

Opps the tailq hash needs to be commented out until I update rack with those files :)

Since we now allow TCP_ACCOUNTING lets make sure it compiles.

This addresses Gleb's comment on the u_x_ type and also creates TCP_ACCOUNTING to address cc's comments
on size.

In D36721#833707, @rscheff wrote:

I have a vage recollection, of something along these lines having been checked in "recently" (within last 2 years?)

Ah, here - https://reviews.freebsd.org/D25016

was that incomplete, or not implemented properly?

It shouldn't matter that much if we reduce cwnd right at the receipt of a new segment (in tcp_input), or just prior of sending out the next segment (in tcp_output)?