This file was schizophrenic when it came to representing sizes. In some
cases it represented them as 'unsigneds', which are not enough for 64-bit
hosts. In other cases, it represented them as uint64_t's, which are
inefficient for 32-bit hosts.
This patch unifies all of the sizes to use size_t instead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19917 91177308-0d34-0410-b5e6-96231b3b80d8