TBufDataset: filter doesn't handle LargeInt fields.

Summary

System Information

• Operating system: Windows 10
• Processor architecture: x86-64
• Compiler version: 3.2.2, trunk
• Device: Laptop

Steps to reproduce

Run attached project

Example Project

program a;

{$mode objfpc}{$H+}

uses
  Classes,
  SysUtils,
  DB,
  BufDataset, bufdataset_parser, dbf_prscore;

var
  Fdb: TBufDataset;
begin
  Fdb := TBufDataset.Create(nil);
  Fdb.FieldDefs.Add('prjid', ftLargeint);
  Fdb.FieldDefs.Add('no', ftString, 10);
  Fdb.CreateDataset;
  Fdb.AppendRecord([0, '0']);
  Fdb.AppendRecord([High(Int64), '1']);
  Fdb.AppendRecord([3556856671915480078, '2']); // ~bk is within range of ftLargeInt
  Fdb.AppendRecord([3556856671915480017, '3']);
  Fdb.AppendRecord([-32767, '4']); // ~bk is within range of ftLargeInt
  WriteLn('RecordCount=', Fdb.RecordCount, ' UNFILTERED');
  with Fdb do begin
    First;
    while not EOF do begin
      WriteLn(FieldByName('prjid').AsString, ' ', FieldByName('no').AsString: 4);
      Next;
    end;
  end;
  Fdb.Filter := 'prjid=-32767 or prjid=3556856671915480078'; // 'prjid=0' -> works
  WriteLn('Filtered with ''', Fdb.Filter, '''');
  Fdb.Filtered := True;
  with Fdb do begin
    First;
    while not EOF do begin
      WriteLn(FieldByName('prjid').AsString, ' ', FieldByName('no').AsString: 4);
      Next;
    end;
  end;

  ReadLn;
end.

What is the current bug behavior?

RecordCount=5 UNFILTERED
0    0
9223372036854775807    1
3556856671915480078    2
3556856671915480017    3
-32767    4
Filtered with 'prjid=-32767 or prjid=3556856671915480078'
-32767    4

What is the expected (correct) behavior?

RecordCount=5 UNFILTERED
0    0
9223372036854775807    1
3556856671915480078    2
3556856671915480017    3
-32767    4
Filtered with 'prjid=-32767 or prjid=3556856671915480078'
3556856671915480078    2
-32767    4

Possible fixes

Proposed patch on trunk dbf_prscore.diff