Fix a lot of problems with the partial destruction of arrays:

Fix a lot of problems with the partial destruction of arrays:
 - an off-by-one error in emission of irregular array limits for
   InitListExprs
 - use an EH partial-destruction cleanup within the normal
   array-destruction cleanup
 - get the branch destinations right for the empty check
Also some refactoring which unfortunately obscures these changes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134890 91177308-0d34-0410-b5e6-96231b3b80d8