Fix up final FPU-registers for FreeBSD x86_64.

[josteink]

FreeBSD now builds without compilation errors. For FreeBSD and glory!

                ,        ,
               /(        )`
               \ \___   / |
               /- _  `-/  '
              (/\/ \ \   /\
              / /   | `    \
              O O   ) /    |
              `-^--'`<     '
             (_.)  _  )   /
              `.___/`    /
                `-----' /
   <----.     __ / __   \
   <----|====O)))==) \) /====
   <----'    `--' `.__,' \
                |        |
                 \       /       /\
            ______( (_  / \______/
          ,'  ,-----'   |
          `--{__________)

This closes https://github.com/dotnet/coreclr/issues/594#issuecomment-93995183

[MattWhilden]

Glorious!

@richlander looks like were closer to needing freebsd CI.

[josteink]

@MattWhilden Just to be intellectually honest: There are build-errors, but all errors related to compilation now seems eliminated.

With linking almost reaching 100% as well, I still think it's fair to call it a milestone though :)

[janvorli]

LGTM

[kangaroo]

LGTM

[MattWhilden]

Sure. Just making sure to have all the pieces in place.