CMake: Fix various bugs in check_01_cxx_features

This commit fixes a typo of the "-std=c++0x" fallback found by Chad Balen
(mailing list).

Furthermore, the fallback logic was also broken (as reported by Wolfgang).
Merge pull request #42 from tamiko/fix_cxx11_setup

CMake: Fix various bugs in check_01_cxx_features
Correct a minor violation of coding standards.