fix checking=fold

fix checking=fold

gcc/

        PR bootstrap/61598
        * fold-const.c (fold_checksum_tree): Use a hash_table of const
        tree_node * instead of tree_node *.
        (fold): Adjust.
        (print_fold_checksum): Likewise.
        (fold_check_failed): Likewise.
        (debug_fold_checksum): Likewise.
        (fold_build1_stat_loc): Likewise.
        (fold_build2_stat_loc): Likewise.
        (fold_build3_stat_loc): Likewise.
        (fold_build_call_array_loc): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@211985 138bc75d-0d04-0410-961f-82ee72b054a4