Fix clang warnings, add clang to travis

Jan Breuer

2015-10-04 df3eeb1a9be519b5eaef18b8f7c2d7a201bf7b97

 examples/test-tcp/main.c

@@ -44,6 +44,7 @@
#include <sys/ioctl.h>
#include <errno.h>
#include <arpa/inet.h>
#include <unistd.h>

#include "scpi/scpi.h"
#include "../common/scpi-def.h"