Fix sss_client breakage.
    
    Adding missing dependencies for linker. Missing dependency was
    introduced by commit 22d381367c27910fe82f476a76b9f4ede555e35a
    in changed file src/sss_client/nss_mc_common.c
    
    All function declaration for io.c was moved from util.h to separate file io.h,
    
    https://fedorahosted.org/sssd/ticket/1838