Upgrade WPILib and upgraded compilers to C++17

I haven't touched the CTRE libraries yet, although they may need to be
upgraded as well.

Note that this change makes it so that you need either Ubuntu 18.04 or
later or debian buster or later in order to build the code (you may be
able to build code for the roborio on older operating systems, but
running the tests will not work normally).

Change-Id: I0cfa37fe37f830edde6d305e1f50414c369098e4
diff --git a/aos/starter/starter.cc b/aos/starter/starter.cc
index 8b137ff..6860cc4 100644
--- a/aos/starter/starter.cc
+++ b/aos/starter/starter.cc
@@ -696,6 +696,8 @@
                   "child %d actually dumped core. "
                   "falling through to killed by signal case\n",
                   pid);
+          [[fallthrough]];
+          /* FALLTHRU */
         case CLD_KILLED:
           // If somebody (possibly us) sent it SIGTERM that means that they just
           // want it to stop, so it stopping isn't a WARNING.
@@ -772,7 +774,7 @@
   // permissions on a roboRIO.
   AOS_CHECK(system("echo 0 > /proc/sys/vm/overcommit_memory") == 0);
 #endif
-  
+
   libevent_base = EventBaseUniquePtr(event_base_new());
 
   std::string core_touch_file = "/tmp/starter.";
@@ -817,7 +819,7 @@
   aos::InitNRT();
 
   std::ifstream list_file(child_list_file);
-  
+
   while (true) {
     std::string child_name;
     getline(list_file, child_name);