Fix ObjectSpace.count_objects document.
Merge pull request #2013 from take-cheeze/objectspace

Fix ObjectSpace.count_objects document.
Fix 'make test' fail to build on Windows(MSVC)
Merge pull request #2014 from kyab/fix_msvc_build_test

Fix 'make test' fail to build on Windows(MSVC)
Add detection of VC++2010 in build_config.rb
Merge pull request #2015 from kyab/detect_vc2010_build_config

Add detection of VC++2010 in build_config.rb