libstdc++: Implement C++26 std::indirect [PR119152]

This patch implements C++26 std::indirect as specified
in P3019 with amendment to move assignment from LWG 4251.

	PR libstdc++/119152

libstdc++-v3/ChangeLog:

	* doc/doxygen/stdheader.cc: Added indirect.h file.
	* include/Makefile.am: Add new header.
	* include/Makefile.in: Regenerate.
	* include/bits/indirect.h: New file.
	* include/bits/version.def (indirect): Define.
	* include/bits/version.h: Regenerate.
	* include/std/memory: Include new header.
	* testsuite/std/memory/indirect/copy.cc
	* testsuite/std/memory/indirect/copy_alloc.cc
	* testsuite/std/memory/indirect/ctor.cc
	* testsuite/std/memory/indirect/incomplete.cc
	* testsuite/std/memory/indirect/invalid_neg.cc
	* testsuite/std/memory/indirect/move.cc
	* testsuite/std/memory/indirect/move_alloc.cc
	* testsuite/std/memory/indirect/relops.cc

Co-authored-by: Tomasz Kamiński <[email protected]>
Signed-off-by: Tomasz Kamiński <[email protected]>

Author: jwakely

libstdc++-v3/doc/doxygen/stdheader.cc

@@ -106,6 +106,7 @@ void init_map()
     headers["uses_allocator.h"]         = "memory";
     headers["uses_allocator_args.h"]    = "memory";
     headers["out_ptr.h"]                = "memory";
+    headers["indirect.h"]               = "memory";
     headers["memory_resource.h"]        = "memory_resource";
     headers["unique_lock.h"]            = "mutex";
     headers["sat_arith.h"]              = "numeric";

libstdc++-v3/include/Makefile.am

@@ -211,6 +211,7 @@ bits_headers = \
 	${bits_srcdir}/gslice_array.h \
 	${bits_srcdir}/hashtable.h \
 	${bits_srcdir}/hashtable_policy.h \
+	${bits_srcdir}/indirect.h \
 	${bits_srcdir}/indirect_array.h \
 	${bits_srcdir}/ios_base.h \
 	${bits_srcdir}/istream.tcc \

libstdc++-v3/include/Makefile.in

@@ -564,6 +564,7 @@ bits_freestanding = \
 @GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/gslice_array.h \
 @GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/hashtable.h \
 @GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/hashtable_policy.h \
+@GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/indirect.h \
 @GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/indirect_array.h \
 @GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/ios_base.h \
 @GLIBCXX_HOSTED_TRUE@	${bits_srcdir}/istream.tcc \