The goal of this header is to reduce code duplication in code dealing
with various minidump constants (and having that code break when new
constants are added). It operates the same way as other llvm .def files:
- a user defines an appropriate macro which specifies the set of constants he wants to work with, and what he wants to do with it
- the user includes the .def file, which will invoke the user-defined macro for all known constants in the given set.
Right now, this defines only three constant sets, which correspond to
the ones I needed in followup patches, but others can (and probably
will) be easily added.