Fix double destruction of objects when OpenMP construct is canceled

When an omp for loop is canceled the constructed objects are being destructed 
twice.

It looks like the desired code is:

{

  Obj o;
  If (cancelled) branch-through-cleanups to cancel.exit.

}
[cleanups]
cancel.exit:

__kmpc_for_static_fini
br cancel.cont (*)

cancel.cont:

__kmpc_barrier
return

The problem seems to be the branch to cancel.cont is currently also going 
through the cleanups calling them again. This change just does a direct branch 
instead.

Patch By: michael.p.rice@intel.com

Differential Revision: https://reviews.llvm.org/D35854

llvm-svn: 309288