[PATCH 02/11] Handle CodeView base types

[PATCH 02/11] Handle CodeView base types

Adds a get_type_num function to translate type DIEs into CodeView
numbers, along with a hash table for this.  For now we just deal with
the base types (integers, Unicode chars, floats, and bools).

gcc/
	* dwarf2codeview.cc (struct codeview_type): New structure.
	(struct die_hasher): Likewise.
	(types_htab): New variable.
	(codeview_debug_finish): Free types_htab if allocated.
	(get_type_num_base_type, get_type_num): New function.
	(add_variable): Call get_type_num.
	* dwarf2codeview.h (T_CHAR, T_SHORT, T_LONG, T_QUAD): Define.
	(T_UCHAR, T_USHORT, T_ULONG, T_UQUAD, T_BOOL08): Likewise.
	(T_REAL32, T_REAL64, T_REAL80, T_REAL128, T_RCHAR): Likewise.
	(T_WCHAR, T_INT4, T_UINT4, T_CHAR16, T_CHAR32, T_CHAR8): Likewise.