Use size_t instead of int64_t for the vector size.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192229 91177308-0d34-0410-b5e6-96231b3b80d8
Fix #endif comment.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@192230 91177308-0d34-0410-b5e6-96231b3b80d8