Enter the cleanups for a block outside the enclosing

Enter the cleanups for a block outside the enclosing
full-expression.  Naturally they're inactive before we enter
the block literal expression.  This restores the intended
behavior that blocks belong to their enclosing scope.

There's a useful -O0 / compile-time optimization that we're
missing here with activating cleanups following straight-line
code from their inactive beginnings.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144268 91177308-0d34-0410-b5e6-96231b3b80d8