Replace gnu::unique_ptr with std::unique_ptr

Replace gnu::unique_ptr with std::unique_ptr

Now that GCC is compiled as C++11 there is no need to keep the C++03
implementation of gnu::unique_ptr.

This removes the unique-ptr.h header and replaces it with <memory> in
system.h, and changes the INCLUDE_UNIQUE_PTR macro to INCLUDE_MEMORY.
Uses of gnu::unique_ptr and gnu::move can be replaced with
std::unique_ptr and std::move. There are no uses of unique_xmalloc_ptr
or xmalloc_deleter in GCC.

gcc/analyzer/ChangeLog:

	* engine.cc: Define INCLUDE_MEMORY instead of INCLUDE_UNIQUE_PTR.

gcc/c-family/ChangeLog:

	* known-headers.cc: Define INCLUDE_MEMORY instead of
	INCLUDE_UNIQUE_PTR.
	* name-hint.h: Likewise.
	(class name_hint): Use std::unique_ptr instead of gnu::unique_ptr.

gcc/c/ChangeLog:

	* c-decl.c: Define INCLUDE_MEMORY instead of INCLUDE_UNIQUE_PTR.
	* c-parser.c: Likewise.

gcc/cp/ChangeLog:

	* error.c: Define INCLUDE_MEMORY instead of
	INCLUDE_UNIQUE_PTR.
	* lex.c: Likewise.
	* name-lookup.c: Likewise.
	(class namespace_limit_reached): Use std::unique_ptr instead of
	gnu::unique_ptr.
	(suggest_alternatives_for): Use std::move instead of gnu::move.
	(suggest_alternatives_in_other_namespaces): Likewise.
	* parser.c: Define INCLUDE_MEMORY instead of INCLUDE_UNIQUE_PTR.

gcc/ChangeLog:

	* Makefile.in: Remove unique-ptr-tests.o.
	* selftest-run-tests.c (selftest::run_tests): Remove
	unique_ptr_tests_cc_tests.
	* selftest.h (unique_ptr_tests_cc_tests): Remove.
	* system.h: Check INCLUDE_MEMORY instead of INCLUDE_UNIQUE_PTR
	and include <memory> instead of "unique-ptr.h".
	* unique-ptr-tests.cc: Removed.

include/ChangeLog:

	* unique-ptr.h: Removed.