Add c++11 option to configure.exe

Also check for c++11 support in configure.exe (which is also used by MinGW builds).
The c++11 check is therefore moved from 'unix' to 'common' directory.

Change-Id: I082848f032c2770e52e34f331b83820f395c06b6
Reviewed-by: Qt Doc Bot <qt_docbot@qt-project.org>
Reviewed-by: Yuchen Deng <loaden@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>