Try to fix cygwin build

Source/CTest/Curl/Platforms/WindowsCache.cmake

@@ -1,3 +1,4 @@
+IF(NOT UNIX)
 IF(WIN32)
   SET(HAVE_LIBWINMM 1)
   SET(HAVE_LIBWS2_32 1)
@@ -106,4 +107,5 @@ IF(WIN32)
 
 ELSE(WIN32)
   MESSAGE("This file should be included on Windows platform only")
-ENDIF(WIN32)
+ENDIF(WIN32)
+ENDIF(NOT UNIX)