Fix evatuated value of __builtin_object_size according to its
'type'  argument when it cannot be determined which objects ptr 
points to at compile time. rdar://18334276


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@218258 91177308-0d34-0410-b5e6-96231b3b80d8