libgo DejaGNU testsuite: Load timeout.exp before go.exp.

http://gcc.gnu.org/PR56017

R=iant
CC=gofrontend-dev
https://codereview.appspot.com/7299073
libgo testsuite: If using DejaGNU, don't frob the log file.

http://gcc.gnu.org/PR56017

R=iant
CC=gofrontend-dev
https://codereview.appspot.com/7299074
compiler, libgo: Permit testing package when test imports it circularly.

R=iant
CC=gofrontend-dev
https://codereview.appspot.com/7299075