BUG: Fix CMAKE_REQUIRED_LIBRARIES stuff in this module

Modules/CheckLibraryExists.cmake

@@ -22,8 +22,6 @@ MACRO(CHECK_LIBRARY_EXISTS LIBRARY FUNCTION LOCATION VARIABLE)
     IF(CMAKE_REQUIRED_LIBRARIES)
       SET(CHECK_LIBRARY_EXISTS_LIBRARIES 
         ${CHECK_LIBRARY_EXISTS_LIBRARIES} ${CMAKE_REQUIRED_LIBRARIES})
-    ELSE(CMAKE_REQUIRED_LIBRARIES)
-      SET(CHECK_LIBRARY_EXISTS_LIBRARIES)
     ENDIF(CMAKE_REQUIRED_LIBRARIES)
     TRY_COMPILE(${VARIABLE}
       ${CMAKE_BINARY_DIR}