Change mangling of objects inside block literals.

This changes the mangling of local static variables/etc. inside blocks
to do something simple and sane.  This avoids depending on the way we mangle
blocks, which isn't really appropriate here.

John, please take a look at this to make sure the mangling I chose is sane.

Fixes <rdar://problem/14074423>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184780 91177308-0d34-0410-b5e6-96231b3b80d8