Clean up printf() argument list.

Splitting %s from \n makes it clearer that the %s's in question take
arguments that already include a newline, and that the subsequent \n
adds a blank line.

Change-Id: I5bac8ca80b42f7de980ad29480042cae3166ff7e
Reviewed-on: https://code.wireshark.org/review/2797
Reviewed-by: Guy Harris <guy@alum.mit.edu>

dumpcap.c

@@ -558,8 +558,10 @@ show_version(GString *comp_info_str, GString *runtime_info_str)
 {
     printf("Dumpcap (Wireshark) %s\n"
            "\n"
-           "%s\n"
-           "%s\n"
+           "%s"
+           "\n"
+           "%s"
+           "\n"
            "%s",
            get_ws_vcs_version_info(), get_copyright_info(), comp_info_str->str, runtime_info_str->str);
 }