In functions whose return type is instantiated from a nested template,
make sure that all members of the instance are emitted before finishing
the outer function, otherwise they will be removed during the
prune_unused_types pass.

gcc/d/ChangeLog:

2019-03-21  Iain Buclaw  <ibuclaw@gdcproject.org>

	PR d/89017
	* d-codegen.cc (d_decl_context): Skip over template instances when
	finding the context.
	* decl.cc (DeclVisitor::visit(TemplateDeclaration)): New override.
	(build_type_decl): Include parameters in name of template types.

gcc/testsuite/ChangeLog:

2019-03-21  Iain Buclaw  <ibuclaw@gdcproject.org>

	PR d/89017
	* gdc.dg/pr89017.d: New test.

From-SVN: r269828