Win32: properly enabled select on Windows. Previously, select was compiled in by default, but the NGX_HAVE_SELECT macro was not set, resulting in iocp being used by default unless the "--with-select_module" configure option was explicitly specified. Since the iocp module is not finished and does not work properly, this effectively meant that the "--with-select_module" option was mandatory. With the change NGX_HAVE_SELECT is properly set, making "--with-select_module" optional. Accordingly, it is removed from misc/GNUmakefile win32 target.