Makefile: Use alternative method to replace *bindir
    
    https://www.gnu.org/software/autoconf/manual/autoconf-2.67/html_node/Installation-Directory-Variables.html
    
    Most of these variables have values that rely on prefix or exec_prefix. It is
    deliberate that the directory output variables keep them unexpanded: typically
    ‘@sbindir@’ is replaced by ‘${exec_prefix}/sbin’, not ‘/usr/local/sbin’.
    This behavior is mandated by the GNU Coding Standards.
    
    Installation directory variables (sbindir, pkgdatadir ...) should be used
    only in makefiles. Similarly, we should not rely on AC_CONFIG_FILES to replace
    sbindir and friends in shell scripts and other files; instead, let make
    manage their replacement.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/2293
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>