Objective-C modern translator. Fix declaration of
__NSConstantStringImpl's length field to accomodate
window's 64bit LLP64 mode. // rdar://16489050


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@205353 91177308-0d34-0410-b5e6-96231b3b80d8