OnDiskHashTable: Expect the Info type to declare the hash size

This changes the on-disk hash to get the size of a hash value from the
Info type, so that clients can be more flexible with the types of hash
they use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206642 91177308-0d34-0410-b5e6-96231b3b80d8
OnDiskHashTable: Expect the Info type to declare the offset type

This changes the on-disk hash to get the type to use for offsets from
the Info type, so that clients can be more flexible with the size of
table they support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206643 91177308-0d34-0410-b5e6-96231b3b80d8