Use if(CYGWIN) instead of if(WIN32 AND UNIX)

CMake has defined CYGWIN on Cygwin for years, so we no longer need the
legacy form of the test.  Change based on patch from issue #10122.

Modules/FindTclsh.cmake

@@ -20,9 +20,9 @@
 # (To distributed this file outside of CMake, substitute the full
 #  License text for the above reference.)
 
-IF(WIN32 AND UNIX)
+IF(CYGWIN)
   FIND_PROGRAM(TCL_TCLSH NAMES cygtclsh83 cygtclsh80)
-ENDIF(WIN32 AND UNIX)
+ENDIF(CYGWIN)
 
 GET_FILENAME_COMPONENT(TK_WISH_PATH "${TK_WISH}" PATH)
 GET_FILENAME_COMPONENT(TK_WISH_PATH_PARENT "${TK_WISH_PATH}" PATH)

Source/CMakeLists.txt

@@ -425,12 +425,12 @@ SET(CPACK_SRCS
   CPack/cmCPackZIPGenerator.cxx
   )
 
-IF(WIN32 AND UNIX)
+IF(CYGWIN)
   SET(CPACK_SRCS ${CPACK_SRCS}
     CPack/cmCPackCygwinBinaryGenerator.cxx
     CPack/cmCPackCygwinSourceGenerator.cxx
     )
-ENDIF(WIN32 AND UNIX)
+ENDIF(CYGWIN)
   
 IF(UNIX)
   SET(CPACK_SRCS ${CPACK_SRCS}