Fix a couple of problems with initialization and assignment to

Fix a couple of problems with initialization and assignment to
__block variables where the act of initialization/assignment
itself causes the __block variable to be copied to the heap
because the variable is of block type and is being assigned
a block literal which captures the variable.

rdar://problem/9814099

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136337 91177308-0d34-0410-b5e6-96231b3b80d8