The -mcygwin option for x86 Windows was removed in 2010 by commit
3edeb30d044a4852881c34229e618b34f95b0d9e, but this reference was
overlooked.
gcc/ChangeLog
PR target/108521
* doc/invoke.texi (Option Summary): Remove -mcygwin and -mno-cygwin
from x86 Windows Options.
-munroll-only-small-loops -mlam=@var{choice}}
@emph{x86 Windows Options}
-@gccoptlist{-mconsole -mcrtdll=@var{library} -mcygwin -mno-cygwin -mdll
+@gccoptlist{-mconsole -mcrtdll=@var{library} -mdll
-mnop-fun-dllimport -mthread
-municode -mwin32 -mwindows -fno-set-stack-executable}