OpenMP/C++: Allow classes with static members to be mappable [PR104493]

OpenMP/C++: Allow classes with static members to be mappable [PR104493]

As this is the last lang-specific user of the omp_mappable_type hook,
the hook is removed, keeping only a generic omp_mappable_type for
incomplete types (or error_node).

	PR c++/104493

gcc/c/ChangeLog:

	* c-decl.cc (c_decl_attributes, finish_decl): Call omp_mappable_type
	instead of removed langhook.
	* c-typeck.cc (c_finish_omp_clauses): Likewise.

gcc/cp/ChangeLog:

	* cp-objcp-common.h (LANG_HOOKS_OMP_MAPPABLE_TYPE): Remove.
	* cp-tree.h (cp_omp_mappable_type, cp_omp_emit_unmappable_type_notes):
	Remove.
	* decl2.cc (cp_omp_mappable_type_1, cp_omp_mappable_type,
	cp_omp_emit_unmappable_type_notes): Remove.
	(cplus_decl_attributes): Call omp_mappable_type instead of
	removed langhook.
	* decl.cc (cp_finish_decl): Likewise; call cxx_incomplete_type_inform
	in lieu of cp_omp_emit_unmappable_type_notes.
	* semantics.cc (finish_omp_clauses): Likewise.

gcc/ChangeLog:

	* gimplify.cc (omp_notice_variable): Call omp_mappable_type
	instead of removed langhook.
	* omp-general.h (omp_mappable_type): New prototype.
	* omp-general.cc (omp_mappable_type):  New; moved from ...
	* langhooks.cc (lhd_omp_mappable_type): ... here.
	* langhooks-def.h (lhd_omp_mappable_type,
	LANG_HOOKS_OMP_MAPPABLE_TYPE): Remove.
	(LANG_HOOKS_FOR_TYPES_INITIALIZER): Remote the latter.
	* langhooks.h (struct lang_hooks_for_types): Remove
	omp_mappable_type.

gcc/testsuite/ChangeLog:

	* g++.dg/gomp/unmappable-1.C: Remove dg-error; remove dg-note no
	longer shown as TYPE_MAIN_DECL is NULL.
	* c-c++-common/gomp/map-incomplete-type.c: New test.

Co-authored-by: Chung-Lin Tang <cltang@codesourcery.com>
(cherry picked from commit 92a5de3df2dc958d6b3d18a0466189ad31f5ae79)