Fix PR52822 (stable_partition move-assigns object to itself) by
scanning for the first value that doesn't match the predicate before
starting to rearrange values.

2012-04-03   Jeffrey Yasskin  <jyasskin@google.com>

	PR libstdc++/52822
	* include/bits/stl_algo.h (__find_if_not): Expose in
	C++98 mode.
	(__find_if_not_n): Like __find_if_not, but works on and updates a
	counted range instead of a bounded range.
	(stable_partition): Guarantee !__pred(*__first) in call to
	__stable_partition_adaptive() or __inplace_stable_partition().
	(__stable_partition_adaptive): Use new precondition to avoid
	moving/copying objects onto themselves.  Guarantee new
	precondition to recursive calls.
	(__inplace_stable_partition): Use new precondition to simplify
	base case, remove __last parameter.  Guarantee new precondition to
	recursive calls.
	* testsuite/25_algorithms/stable_partition/moveable.cc (test02):
	Test a sequence that starts with a value matching the predicate.
	* testsuite/25_algorithms/stable_partition/pr52822.cc:
	Test vectors, which have a destructive self-move-assignment.

From-SVN: r186391