* flags.h (enum debug_info_type): Remove DWARF_DEBUG.
	* defaults.h (PREFERRED_DEBUGGING_TYPE): Remove check for
	DWARF_DEBUGGING_INFO from choice-of-definition chain;
	restructure using C89 features (#elif, #error).
	* c-lex.c, final.c, opts.c, config/cris/cris.c, config/frv/frv.c
	* config/sh/sh.h: Remove references to DWARF_DEBUG.
	* doc/invoke.texi: Remove references to DWARF version 1;
	clarify why -gdwarf-2<n> doesn't work.
cp:
	* class.c, search.c: Remove references to DWARF_DEBUG.

From-SVN: r86540