[PATCH] Fix typo in std::stack (PR libstdc++/81599)

[Marek Polacek]

The documentation of std::stack says that the underlying container must support
pop_front, but that is wrong, it meant to say pop_back, so this patch fixes
that.

Ok for trunk?

2017-07-31  Marek Polacek  <polacek@redhat.com>

	PR libstdc++/81599
	* include/bits/stl_stack.h: Fix typo.

diff --git gcc/include/bits/stl_stack.h gcc/include/bits/stl_stack.h
index ac59ec715cf..5f2b4ab4486 100644
--- gcc/include/bits/stl_stack.h
+++ gcc/include/bits/stl_stack.h
@@ -86,7 +86,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *
    *  The second template parameter defines the type of the underlying
    *  sequence/container.  It defaults to std::deque, but it can be
-   *  any type that supports @c back, @c push_back, and @c pop_front,
+   *  any type that supports @c back, @c push_back, and @c pop_back,
    *  such as std::list, std::vector, or an appropriate user-defined
    *  type.
    *

	Marek