c++: Implement C++26 P3920R0 - Wording for NB comment resolution on trivial relocation

c++: Implement C++26 P3920R0 - Wording for NB comment resolution on trivial relocation

Trivial relocation was voted out of C++26, the following patch
removes it (note, the libstdc++ part was still waiting for patch review
and so doesn't need to be removed).

This isn't a mere revert of r16-2206; I've kept -Wc++26-compat option,
from earlier patches the non-terminal stays to be class-property-specifier,
and I had to partially revert also various follow-up changes, e.g. for
modules to handle the new flags and test them, for -Wkeyword-macro
etc. to diagnose the conditional keywords or the feature test macro
etc.

2025-11-10  Jakub Jelinek  <jakub@redhat.com>

	PR c++/119064
gcc/c-family/
	* c-cppbuiltin.cc (c_cpp_builtins): Revert 2025-07-11
	changes.
gcc/cp/
	* cp-tree.h (struct lang_type): Revert 2025-07-11 changes.
	(CLASSTYPE_TRIVIALLY_RELOCATABLE_BIT): Remove.
	(CLASSTYPE_TRIVIALLY_RELOCATABLE_COMPUTED): Remove.
	(CLASSTYPE_REPLACEABLE_BIT): Remove.
	(CLASSTYPE_REPLACEABLE_COMPUTED): Remove.
	(enum virt_specifier): Revert 2025-07-11 changes.
	(trivially_relocatable_type_p): Remove.
	(replaceable_type_p): Remove.
	* cp-trait.def (IS_NOTHROW_RELOCATABLE): Remove.
	(IS_REPLACEABLE): Remove.
	(IS_TRIVIALLY_RELOCATABLE): Remove.
	* parser.cc (cp_parser_class_specifier, cp_parser_class_head):
	Revert 2025-07-11 changes.
	* pt.cc (instantiate_class_template): Likewise.
	* semantics.cc (trait_expr_value): Likewise.
	(finish_trait_expr): Likewise.
	* tree.cc (default_movable_type_p): Remove.
	(union_with_no_declared_special_member_fns): Remove.
	(trivially_relocatable_type_p): Remove.
	(replaceable_type_p): Remove.
	* constraint.cc (diagnose_trait_expr): Revert 2025-07-11 changes.
	* module.cc (trees_out::lang_type_bools): Revert part of
	2025-07-26 changes related to trivial relocatability.
	(trees_in::lang_type_bools): Likewise.
	* lex.cc (cxx_init): Don't call cpp_warn on
	trivially_relocatable_if_eligible and replaceable_if_eligible.
gcc/testsuite/
	* g++.dg/cpp26/feat-cxx26.C: Revert 2025-07-11 changes.
	* g++.dg/DRs/dr2581-1.C (__cpp_trivial_relocatability): Remove test.
	* g++.dg/DRs/dr2581-2.C (__cpp_trivial_relocatability): Likewise.
	* g++.dg/warn/Wkeyword-macro-1.C: Don't expect any diagnostics on
	#define or #undef of trivially_relocatable_if_eligible or
	replaceable_if_eligible.
	* g++.dg/warn/Wkeyword-macro-2.C: Likewise.
	* g++.dg/warn/Wkeyword-macro-4.C: Likewise.
	* g++.dg/warn/Wkeyword-macro-5.C: Likewise.
	* g++.dg/warn/Wkeyword-macro-7.C: Likewise.
	* g++.dg/warn/Wkeyword-macro-8.C: Likewise.
	* g++.dg/cpp26/trivially-relocatable1.C: Remove.
	* g++.dg/cpp26/trivially-relocatable2.C: Remove.
	* g++.dg/cpp26/trivially-relocatable3.C: Remove.
	* g++.dg/cpp26/trivially-relocatable4.C: Remove.
	* g++.dg/cpp26/trivially-relocatable5.C: Remove.
	* g++.dg/cpp26/trivially-relocatable6.C: Remove.
	* g++.dg/cpp26/trivially-relocatable7.C: Remove.
	* g++.dg/cpp26/trivially-relocatable8.C: Remove.
	* g++.dg/cpp26/trivially-relocatable9.C: Remove.
	* g++.dg/cpp26/trivially-relocatable10.C: Remove.
	* g++.dg/cpp26/trivially-relocatable11.C: Remove.
	* g++.dg/modules/class-11_a.H: Remove trivial relocatability
	related parts.
	* g++.dg/modules/class-11_b.C: Likewise.