* deduplicates exprToString, defined in multiple packages, and moves it
to astutil
* moves resolveTypedef into pkg/dwarf/godwarf, this is currently only
used by pkg/proc but we will need to call it from pkg/proc/evalop
* creates a new FakePointerType function in pkg/dwarf/godwarf, this is
also a function that is only used by pkg/proc but pkg/proc/evalop will
also need.
Updates #1465