Fix a server side crash with -P and -R.

The problem was a mangled printf format string, which I introduced in
616ac79bd80b.

Issue:		129 (iperf3 hangs with -R and -Z flags)

src/locale.c

@@ -256,7 +256,7 @@ const char report_sum_bw_format[] =
 "[SUM] %6.2f-%-6.2f sec  %ss  %ss/sec              %s\n";
 
 const char report_sum_bw_retrans_format[] =
-"[SUM] %6.2f-%-6.2f sec  %ss  %ss/sec              %s\n";
+"[SUM] %6.2f-%-6.2f sec  %ss  %ss/sec  %3d         %s\n";
 
 const char report_sum_bw_udp_format[] =
 "[SUM] %6.2f-%-6.2f sec  %ss  %ss/sec  %5.3f ms  %d/%d (%.2g%%)  %s\n";