d: Build internal TypeInfo types when module name is "object"

If for whatever reason the module declaration doesn't exist in the
object file, ensure that the internal definitions for TypeInfo and
TypeInfo_Class are still created, otherwise an ICE could occur later if
they are required for a run-time helper call.

gcc/d/ChangeLog:

	* d-compiler.cc (Compiler::onParseModule): Call create_tinfo_types
	when module name is object.
	* typeinfo.cc (create_tinfo_types): Add guard for multiple
	invocations.