BUILD: Add missing deps to libsss_sbus*.so
    
    It indirectly caused failures when linking unit test.
    
      CCLD     test_sbus_opath
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_utf8_validate'
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_free'
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_malloc'
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_utf8_casefold'
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_utf8_collate'
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_utf8_strlen'
    /usr/bin/ld: ./.libs/libsss_sbus.so: undefined reference to `g_utf8_strdown'
    
    Merges: https://pagure.io/SSSD/sssd/pull-request/3808
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>