protected DebugInfoEntry addSubroutineType(String name, DebugInfoEntry returnTypeDIE) {
		ensureCompUnit();
		DIECreator tmp = new DIECreator(dwarfProg, DW_TAG_subroutine_type);
		if (name != null) {
			tmp.addString(DW_AT_name, name);
		}
		if (returnTypeDIE != null) {
			tmp.addRef(DW_AT_type, returnTypeDIE);
		}
		return tmp.create();
	}
Base class for unit tests needing DWARF DIEs.  Provides 2 DWARF compile-units and helper
methods to create DIE records.
Ghidra/Features/Base/src/test/java/ghidra/app/util/bin/format/dwarf/DWARFTestBase.java