[PATCH] Fix libstdc++ versioned namespace build

[Jonathan Wakely <jwakely at redhat dot com>]

The versioned namespace build has been broken on all branches for some
time. It's due to new code that doesn't use the namespace macros in
the right places. This fixes all issues.

Rather than declaring the std::experimental::* namespaces in
<bits/c++config.h> I've added a new file that declares them and is
only included by LFTS headers. That allows the new test to pass, which
verifies that the std::experimental namespace doesn't exist when no TS
headers are included.

	PR libstdc++/68323
	PR libstdc++/77794
	* config/abi/pre/gnu-versioned-namespace.ver: Add exports for
	__cxa_thread_atexit and __gnu_cxx::__freeres.
	* include/Makefile.am: Add <experimental/bits/lfts_config.h>
	* include/Makefile.in: Regenerate.
	* include.bits/basic_string.h: Fix nesting of versioned namespaces.
	* include/bits/c++config: Declare versioned namespaces for literals.
	* include/bits/regex.h (basic_regex, match_results): Add workarounds
	for PR c++/59256.
	* include/bits/uniform_int_dist.h: Fix nesting of versioned namespace.
	* include/std/chrono: Likewise.
	* include/std/complex: Likewise.
	* include/std/string_view: Likewise.
	* include/std/variant: Likewise. Add workaround for PR c++/59256.
	* include/experimental/bits/fs_fwd.h: Declare versioned namespace.
	* include/experimental/bits/lfts_config.h: Declare versioned
	namespaces.
	* include/experimental/algorithm: Include
	<experimental/bits/lfts_config.h>.
	* include/experimental/any: Likewise.
	* include/experimental/bits/erase_if.h: Likewise.
	* include/experimental/chrono: Likewise.
	* include/experimental/functional: Likewise.
	* include/experimental/memory_resource: Likewise.
	* include/experimental/optional: Likewise.
	* include/experimental/propagate_const: Likewise.
	* include/experimental/random: Likewise.
	* include/experimental/ratio: Likewise.
	* include/experimental/system_error: Likewise.
	* include/experimental/tuple: Likewise.
	* include/experimental/type_traits: Likewise.
	* include/experimental/utility: Likewise.
	* include/experimental/string_view: Likewise. Fix nesting of
	versioned namespaces.
	* include/experimental/bits/string_view.tcc: Reopen inline namespace
	for non-inline function definitions.
	* testsuite/17_intro/using_namespace_std_exp_neg.cc: New test.
	* testsuite/20_util/duration/literals/range.cc: Adjust dg-error line.
	* testsuite/experimental/any/misc/any_cast_neg.cc: Likewise.
	* testsuite/experimental/propagate_const/assignment/move_neg.cc:
	Likewise.
	* testsuite/experimental/propagate_const/cons/move_neg.cc: Likewise.
	* testsuite/experimental/propagate_const/requirements2.cc: Likewise.
	* testsuite/experimental/propagate_const/requirements3.cc: Likewise.
	* testsuite/experimental/propagate_const/requirements4.cc: Likewise.
	* testsuite/experimental/propagate_const/requirements5.cc: Likewise.
	* testsuite/ext/profile/mutex_extensions_neg.cc: Likewise.

Tested x86_64-linux, with --enable-symvers=gnu-versioned-namespace and
--enable-symvers=gnu, on trunk and gcc-6 and gcc-5 branches.

The only failures are in synopsis.cc tests which expect to be able to
redeclare names in namespace std (which is ambiguous if they're really
declared in std::__7) or in tests that use scan-assembler or GDB and
the expected strings are different due to the __7 namespace. I will
probably add an effective target for the versioned namespace so we can
disable those tests when they're going to fail.

Committed to trunk and gcc-6 and gcc-5 branches.

Attachment: patch.txt
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