* etags.c (Cplusplus_suffixes): Add .M suffix for Objective C++.

* etags.c (Cplusplus_suffixes): Add .M suffix for Objective C++.
	(gperf): Added keywords for Objective C and GNU macros.
	(sym_type): Added values to account for Objective C and GNU macros.
	(begtk): The '@' character can start a token.
	(objdef, methodlen, objtag): New variables for Objective C.
	(consider_token, C_entries): Added code for Objective C.
	(plain_C_suffixes): Add .m and .lm for Objective C.
	(Yacc_suffixes): Add .ym for Objective yacc.
	(GROW_LINEBUFFER): New macro.
	(consider_token, C_entries, Pascal_functions): Use the new macro.
	(consider_token): Take one more argument.  Caller changed.
	(consider_token): Use the hashing function to spot GNU macros.
	(C_entries): Consider // as a comment start even in plain C for
	the sake of Objective C parsing.
	(pfnote): Don't make a tag for ctags if there is no name.
	(getit, Asm_labels, Perl_functions, Pascal_functions, L_getit,
	get_scheme, prolog_getit): Name the tag in ctags mode.
	(pfnote): Truncate ctags lines to 50 chars, like it worked once.
	(Perl_interpreters): Accept "@PERL@" as an interpreter.
	(suggest_asking_for_help): New function.
	(main, get_language_from_name): Use suggest_asking_for_help.
	(main): Let get_language_from_name make language existence check.
	(streq, strneq): Check the arguments #if DEBUG.