Many calls to Function::GetAddressRange() were not interested in the
range itself. Instead they wanted to find the address of the function
(its entry point) or the base address for relocation of function-scoped
entities (technically, the two don't need to be the same, but there's
isn't good reason for them not to be). This PR creates a separate
function for retrieving this, and changes the existing
(non-controversial) uses to call that instead.
Update the error returns in ValueObject::CastToBasicType and
ValueObject::CastToEnumType to create new errors and return a
ValueObjectConstResult with the error, rather tnan updating the error in
(and returning) the input ValueObject.
This reverts commit 25909b811a7ddc983d042b15cb54ec271a673d63 due to
unresolved questions about the behavior of "frame var" and ValueObject
in the presence of references (see the original patch for discussion).
ValueObject is part of lldbCore for historical reasons, but conceptually
it deserves to be its own library. This does introduce a (link-time) circular
dependency between lldbCore and lldbValueObject, which is unfortunate
but probably unavoidable because so many things in LLDB rely on
ValueObject. We already have cycles and these libraries are never built
as dylibs so while this doesn't improve the situation, it also doesn't
make things worse.
The header includes were updated with the following command:
```
find . -type f -exec sed -i.bak "s%include \"lldb/Core/ValueObject%include \"lldb/ValueObject/ValueObject%" '{}' \;
```
