Previously we would dump the names of enum types, but not their
enumerator values. This adds support for enumerator values. In
doing so, we have to introduce a general purpose mechanism for
caching symbol indices of field list members. Unlike global
types, FieldList members do not have a TypeIndex. So instead,
we identify them by the pair {TypeIndexOfFieldList, IndexInFieldList}.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342415 91177308-0d34-0410-b5e6-96231b3b80d8
