Fix compilation problems with clang

Apparently, clang presents itself as gcc 4.2 even though it supports the final version of rvalue references. Restrict the workaround to gcc only.
Merge pull request #6 from Lastique/patch-3

Fix compilation problems with clang
Rename member because _CRTDBG_MAP_ALLOC in VS does not allow it

_CRTDBG_MAP_ALLOC has issues with member functions named "free".
Avoid potential conflict between AIX's and Lambda's var.

In ../boost/lambda/detail/lambda_functor_base.hpp there is variable called var that conflicts with an AIX system variable. The entire file (sched.h) does not need to be included only the one function it uses (sched_yield).
Merge branch 'aix_fix' of https://github.com/ibmsoe/smart_ptr into develop
Add shared_from_raw tests.
Fix shared_from_raw_test4 failures.
Rename esft_constructor_test.cpp to shared_from_raw_test5.cpp.
Rename enable_shared_from_raw_test.cpp to weak_from_raw_test.cpp.
Extend nullptr_t workaround to Intel C++.
Fix sp_nullptr_test for compilers that don't define std::nullptr_t.
Merge branch 'develop'