Define Fortran derived types that describe the characteristics
of derived types, and instantiations of parameterized derived
types, that are of relevance to the runtime language support
library. Define a suite of corresponding C++ structure types
for the runtime library to use to interpret instances of the
descriptions.
Create instances of these description types in Semantics as
static initializers for compiler-created objects in the scopes
that define or instantiate user derived types.
Delete obsolete code from earlier attempts to package runtime
type information.
Differential Revision: https://reviews.llvm.org/D92802
