configure: Fix detection of supported NSS db type
    
    For now configure always reports about the lack of support for
    any NSS db:
    checking if NSS supports "sql:" databases... no
    checking if NSS supports "dbm:" databases... no
    
    Actually, there is the linking issue, but AC_TRY_RUN is not
    designed to detect this.
    
    The recipe is the obeying the proper linking order:
    $CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS
    
    Fixes: https://pagure.io/certmonger/issue/153
    Signed-off-by: Stanislav Levin <slev@altlinux.org>