--show-error: position indepdenent

Previously we required that -S/--show-error was used _after_
-s/--silent. This was slightly confusing since we strive to make
arguments as position independent as possible.

Now, you can use them in any order and the result should still be the
same.

Bug: http://curl.haxx.se/bug/view.cgi?id=3424286
Reported by: Andreas Olsson