CONFIG+=debug_and_release is set only on Windows

This is the continuation of QTCREATORBUG-13807

When building software from different components, you often need to link to libraries from other subprojects.

As debug_and_release is active by default on Windows, the paths to the libraries are different from the paths on Linux or Mac.

• It's unclear why debug_and_release is set on Windows and not for the other OS
• Especially in Qt Creator, which creates shadow-build directories, it's hard to specifiy the path to a library or executeable file
• For me it's also unclear if I can safely set CONFIG-=debug_and_release or if there are side-effects.
• As it was unknown for me that I can disable the extra debug and release subdirectories for six years, there is surely some documentation missing.
• I'd at lease like some help from Qt Creators project wizards, but this was rejected by Tobias