Add dotted version of Dos unit in msdos/sysutils source

rtl/msdos/sysutils.pp

@@ -390,7 +390,7 @@ begin
   //!! Sr := New(PSearchRec);
   getmem(sr,sizeof(searchrec));
   Rslt.FindHandle := Sr;
-  DOS.FindFirst(Path, Attr, Sr^);
+  {$IFDEF FPC_DOTTEDUNITS}TP.{$endif}DOS.FindFirst(Path, Attr, Sr^);
   result := -DosError;
   if result = 0 then
    begin
@@ -410,7 +410,7 @@ begin
   Sr := PSearchRec(Rslt.FindHandle);
   if Sr <> nil then
    begin
-     DOS.FindNext(Sr^);
+     {$IFDEF FPC_DOTTEDUNITS}TP.{$endif}DOS.FindNext(Sr^);
      result := -DosError;
      if result = 0 then
       begin
@@ -433,7 +433,7 @@ begin
     begin
       //!! Dispose(Sr);
       // This call is non dummy if LFNSupport is true PM
-      DOS.FindClose(SR^);
+      {$IFDEF FPC_DOTTEDUNITS}TP.{$endif}DOS.FindClose(SR^);
       freemem(sr,sizeof(searchrec));
     end;
   Handle := nil;
@@ -883,16 +883,16 @@ var
   CommandLine: RawByteString;
 
 begin
-  dos.exec_ansistring(path,comline);
+  {$IFDEF FPC_DOTTEDUNITS}TP.{$endif}dos.exec_ansistring(path,comline);
 
-  if (Dos.DosError <> 0) then
+  if ({$IFDEF FPC_DOTTEDUNITS}TP.{$endif}Dos.DosError <> 0) then
     begin
       if ComLine <> '' then
        CommandLine := Path + ' ' + ComLine
       else
        CommandLine := Path;
-      e:=EOSError.CreateFmt(SExecuteProcessFailed,[CommandLine,Dos.DosError]);
-      e.ErrorCode:=Dos.DosError;
+      e:=EOSError.CreateFmt(SExecuteProcessFailed,[CommandLine,{$IFDEF FPC_DOTTEDUNITS}TP.{$endif}Dos.DosError]);
+      e.ErrorCode:={$IFDEF FPC_DOTTEDUNITS}TP.{$endif}Dos.DosError;
       raise e;
     end;
   Result := DosExitCode;