Fix cross-tool check for readelf This makes all stages of newlib's configury set $READELF to the proper cross-tool. This solves the problem that the configure test for .init_array support would get the wrong answer on Mac, because it was trying to use the native readelf and there wasn't any. BUG= http://code.google.com/p/nativeclient/issues/detail?id=1096 TEST= toolchain trybot [email protected] Review URL: http://codereview.chromium.org/8372081