bugfix: tester compiles again

lib/pure/streams.nim

@@ -170,7 +170,7 @@ proc readLine*(s: PStream, line: var TaintedString): bool =
   ## ``CRLF``. The newline character(s) are not part of the returned string.
   ## Returns ``false`` if the end of the file has been reached, ``true``
   ## otherwise. If ``false`` is returned `line` contains no new data.
-  line.setLen(0)
+  line.string.setLen(0)
   while true:
     var c = readChar(s)
     if c == '\c': 

lib/system/sysio.nim

@@ -42,7 +42,7 @@ proc raiseEIO(msg: string) {.noinline, noreturn.} =
 proc readLine(f: TFile, line: var TaintedString): bool =
   # of course this could be optimized a bit; but IO is slow anyway...
   # and it was difficult to get this CORRECT with Ansi C's methods
-  setLen(line, 0) # reuse the buffer!
+  setLen(line.string, 0) # reuse the buffer!
   while True:
     var c = fgetc(f)
     if c < 0'i32: