Patch to support pre-c++11 compiler

[GoogleCodeExporter]

Hi, All, I made some changes for old gcc:

* Add a btree_config.h
* Config type_traits according to whether c++11 is support and enabled by 
compiler.
* Allow user define size_type to be size_t, which make the size() interface of 
btree containers compatible with STL totally.
* Remove dependency of the __COUNTER__ macro in bench test, which was 
introduced since gcc 4.3, make cpp-btree compile with older compiler.

Tested on gcc 4.1.2 & 4.7.2, w/ & w/o c++11 enabled.

Original issue reported on code.google.com by chen3feng on 8 Apr 2013 at 5:00

Attachments:

• cpp-btree-1.0.1-non-c++11.patch