This doesn't attempt to move every decorator. The reason for
this is that it requires touching every single test file to import
decorators.py. I would like to do this in a followup patch, but
in the interest of keeping the patches as bite-sized as possible,
I've only attempted to move the underlying common decorators first.
A few tests call these directly, so those tests are updated as part
of this patch.
llvm-svn: 259807
