Workarounds for MSVC

Here are two workarounds for MSVC.

- First (687668c), it affects VS2015 Preview only, but I believe there is no performance, syntactic and any other regressions. Thus it can be merged straightforward.
  - will fix [adapt_adt / msvc-14.0](http://www.boost.org/development/tests/develop/developer/output/teeks99-08f-win2012R2-64on64-boost-bin-v2-libs-fusion-test-adapt_adt-test-msvc-14-0-debug-threading-multi.html) and so on ...

- Second <del>(2c64426)</del>(9ab7774, comment updated and no other changes), it affects all of rvalue-reference available MSVC (>= 10.0). For more details, see [inline comment](https://github.com/Flast/fusion/blob/2c6442682e080df06d535c5d3c2beed43ce4651b/include/boost/fusion/support/config.hpp#L44-L68).
  - will fix [map_comparison / msvc-10.0](http://www.boost.org/development/tests/develop/developer/output/teeks99-08c-win2012R2-64on64-boost-bin-v2-libs-fusion-test-map_comparison-test-msvc-10-0-debug-threading-multi.html), [map_construction / msvc-10.0](http://www.boost.org/development/tests/develop/developer/output/teeks99-08c-win2012R2-64on64-boost-bin-v2-libs-fusion-test-map_construction-test-msvc-10-0-debug-threading-multi.html) and so on ...


Tested compilers
- GCC 4.9.2 (c++98, c++11, c++14 mode)
- Clang 3.5.0 (c++98, c++11, c++14 mode)
- MSVC
  - 8.0 (2005 EE)
  - 9.0 (2008 Pro)
  - 10.0 (2010 EE)
  - 11.0 (2012 EE)
  - 12.0 (2013 EE)
  - 14.0 (VS 2015 Preview)