[Bug #20989] Ripper: Pass `compile_error`

	For the universal parser, `rb_parser_reg_fragment_check` function is
	shared between the parser and ripper.  However `parser_params` struct
	is partially different, and `compile_error` function depends on that
	part indirectly.

For the universal parser, `rb_reg_named_capture_assign_iter_impl`
function is shared between the parser and ripper.  However
`parser_params` struct is partially different, and `assignable`
function depends on that part indirectly.

For example, the following code leaks:

    class MyRipper < Ripper
      def initialize(src, &blk)
        super(src)
        @blk = blk
      end

      def warn(msg, *args) = @blk.call(msg)
    end

    $VERBOSE = true
    def call_parse = MyRipper.new("if true\n  end\n") { |msg| return msg }.parse

    10.times do
      500_000.times do
        call_parse
      end

      puts `ps -o rss= -p #{$$}`
    end

Before:

    37536
    53744
    70064
    86448
    102576
    119120
    135248
    151216
    167744
    183824

After:

    19280
    19696
    19728
    20336
    20448
    21408
    21616
    21616
    21824
    21840

For example, the following code leaks:

    class MyRipper < Ripper
      def initialize(src, &blk)
        super(src)
        @blk = blk
      end

      def warn(msg, *args) = @blk.call(msg)
    end

    $VERBOSE = true
    def call_parse = MyRipper.new("if true\n  end\n") { |msg| return msg }.parse

    10.times do
      500_000.times do
        call_parse
      end

      puts `ps -o rss= -p #{$$}`
    end

Before:

    34832
    51952
    69760
    88048
    105344
    123040
    141152
    159152
    176656
    194272

After:

    18400
    20256
    20272
    20272
    20272
    20304
    20368
    20368
    20368
    20400

For example, the following script leaks:

    class MyRipper < Ripper
      def initialize(src, &blk)
        super(src)
        @blk = blk
      end

      def compile_error(msg) = @blk.call(msg)
    end

    def call_parse = MyRipper.new("/") { |msg| return msg }.parse

    10.times do
      100_000.times do
        call_parse
      end

      puts `ps -o rss= -p #{$$}`
    end

Before:

    93952
    169040
    244224
    318784
    394432
    468224
    544048
    618560
    693776
    768384

After:

    19776
    19776
    20352
    20880
    20912
    21408
    21328
    21152
    21472
    20944

Fallback to the last token element in that case, for the backward
compatibilities.

Fix up 89cfc1520717257073012ec07105c551e4b8af7c.