Broken pretty printers for std::map in C++11

[François Dumont]

Hi

     I just wanted to let you know that the pretty printer script is 
broken when building code containing a tree based container in C++11. 
This is so since std::map & co have been made C++11 allocator-aware 
because in this mode _Rb_tree_node<_Val> doesn't have a _M_value_field 
anymore.

     I don't really know how to handle it so I prefer to report it first 
if you want to fix it for 4.9 release.

François