[Issue 5093] improve error for importing std.c.windows.windows

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=5093

b2.t...@gmx.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|phobos                      |dmd
                 OS|Linux                       |All

--