PR debug/38757 gcc does not emit DW_LANG_C99.

For C and C++ add the language standard version in use to lang_hooks.name.
Change users of lang_hook.name to check with new functions lang_GNU_C or
lang_GNU_CXX. In dwarf2out.c output the DW_LANG_C version from the
lang_hooks.name and merge any LTO TRANSLATION_UNIT_LANGUAGE found. Adds
two testcases to dwarf2.exp to check the right DWARF DW_AT_language is set
on the compile_unit depending on the -std=c89 or -std=c99 setting.

gcc/c-family/ChangeLog

	PR debug/38757
	* c-opts.c (set_std_c89): Set lang_hooks.name.
	(set_std_c99): Likewise.
	(set_std_c11): Likewise.
	(set_std_cxx98): Likewise.
	(set_std_cxx11): Likewise.
	(set_std_cxx14): Likewise.
	(set_std_cxx1z): Likewise.

gcc/ChangeLog

	PR debug/38757
	* config/avr/avr-c.c (avr_cpu_cpp_builtins): Use lang_GNU_C.
	* config/darwin.c (darwin_file_end): Use lang_GNU_CXX.
	(darwin_override_options): Likewise.
	* config/ia64/ia64.c (ia64_struct_retval_addr_is_first_parm_p):
	Likewise.
	* config/rs6000/rs6000.c (rs6000_output_function_epilogue):
	Likewise.
	* dbxout.c (get_lang_number): Likewise.
	(dbxout_type): Likewise.
	(dbxout_symbol_location): Likewise.
	* dwarf2out.c (add_prototyped_attribute): Add DW_AT_prototype
	also for DW_LANG_{C,C99,ObjC}.
	(highest_c_language): New function.
	(gen_compile_unit_die): Call highest_c_language to merge LTO
	TRANSLATION_UNIT_LANGUAGE. Use strncmp language_string to
	determine if DW_LANG_C99 or DW_LANG_C89 should be returned.
	* fold-const.c (fold_cond_expr_with_comparison): Use lang_GNU_CXX.
	* langhooks.h (struct lang_hooks): Add version comment to name.
	(lang_GNU_C): New function declaration.
	(lang_GNU_CXX): Likewise.
	* langhooks.c (lang_GNU_C): New function.
	(lang_GNU_CXX): Likewise.
	* vmsdbgout.c (vmsdbgout_init): Use lang_GNU_C and lang_GNU_CXX.

gcc/testsuite/ChangeLog

	PR debug/38757
	* gcc.dg/debug/dwarf2/lang-c89.c: New test.
	* gcc.dg/debug/dwarf2/lang-c99.c: Likewise.

From-SVN: r217934