cmake HAVE_SYSENT_H examples

alibaba/AliSQL configure.cmake :375 

CHECK_INCLUDE_FILES (sysent.h HAVE_SYSENT_H)

arkdb/arkproxy configure.cmake :213 

CHECK_INCLUDE_FILES (sysent.h HAVE_SYSENT_H)

alibaba/AliSQLBackup configure.cmake :291 

CHECK_INCLUDE_FILES (sysent.h HAVE_SYSENT_H)