re PR c/90677 (gcc-9.1.0 fails to build __gcc_diag__ souce: error: 'cgraph_node' is not defined as a type)

	PR c/90677
	* c-common.h (identifier_global_tag): Declare.
	* c-format.c (get_pointer_to_named_type): Renamed to ...
	(get_named_type): ... this.  Use identifier_global_tag instead of
	identifier_global_value, handle the return value being a TYPE_P.
	(init_dynamic_diag_info): Adjust get_pointer_to_named_type callers
	to call get_named_type instead.  Formatting fixes.
c/
	* c-decl.c (identifier_global_tag): Define.
cp/
	* cp-objcp-common.c (identifier_global_tag): Define.
testsuite/
	* c-c++-common/pr90677.c: New test.

From-SVN: r278634