[tests] fix includes in libc

Does not work on macOS ; probably implicit path lookup is different than linux ?

share/libc/netinet/in.h

@@ -25,7 +25,7 @@
 
 #ifndef __FC_NETINET_IN
 #define __FC_NETINET_IN
-#include "features.h"
+#include "../features.h"
 __PUSH_FC_STDLIB
 #include "../__fc_inet.h"
 __POP_FC_STDLIB

share/libc/sys/socket.h

@@ -46,7 +46,7 @@ struct sockaddr_storage {
   sa_family_t   ss_family;
 };
 
-#include "sys/uio.h"
+#include "./uio.h"
 
 struct cmsghdr {
   socklen_t  cmsg_len;