--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

src/tool_getparam.c

@@ -1426,11 +1426,15 @@ ParameterError getparameter(char *flag,    /* f or -long-flag */
         config->mute = config->noprogress = TRUE;
       else
         config->mute = config->noprogress = FALSE;
-      config->showerror = (!toggle)?TRUE:FALSE; /* toggle off */
+      if(config->showerror < 0)
+        /* if still on the default value, set showerror to the reverse of
+           toggle. This is to allow -S and -s to be used in an independent
+           order but still have the same effect. */
+        config->showerror = (!toggle)?TRUE:FALSE; /* toggle off */
       break;
     case 'S':
       /* show errors */
-      config->showerror = toggle; /* toggle on if used with -s */
+      config->showerror = toggle?1:0; /* toggle on if used with -s */
       break;
     case 't':
       /* Telnet options */