Update WPILib, roborio compilers, and CTRE Phoenix libraries

This borrows heavily from work that Ravago did to initially get this
stuff working.

Tested rudimentary functionality on a test bench, ensured that we could:
* Enable the robot.
* Read joystick and button values.
* Switch between auto and teleop modes.
* Read sensor values (encoder, absolute encoder, potentiometer).
* Read PDP values.
* Drive PWM motors.
* Drive CANivore motors.

Non-WPILib changes are made to accommodate the upgrade roborio
compiler's improved pickiness.

Merge commit '125aac16d9bf03c833ffa18de2f113a33758a4b8' into HEAD

Change-Id: I8648956fb7517b2d784bf58e0a236742af7a306a
Signed-off-by: James Kuszmaul <jabukuszmaul+collab@gmail.com>
diff --git a/frc971/constants/constants_sender_lib.h b/frc971/constants/constants_sender_lib.h
index 6c849c3..92c14fa 100644
--- a/frc971/constants/constants_sender_lib.h
+++ b/frc971/constants/constants_sender_lib.h
@@ -14,17 +14,14 @@
 template <typename ConstantsData, typename ConstantsList>
 class ConstantSender {
  public:
-  ConstantSender<ConstantsData, ConstantsList>(
-      aos::EventLoop *event_loop, std::string constants_path,
-      std::string_view channel_name = "/constants")
+  ConstantSender(aos::EventLoop *event_loop, std::string constants_path,
+                 std::string_view channel_name = "/constants")
       : ConstantSender<ConstantsData, ConstantsList>(
             event_loop, constants_path, aos::network::GetTeamNumber(),
             channel_name) {}
 
-  ConstantSender<ConstantsData, ConstantsList>(aos::EventLoop *event_loop,
-                                               std::string constants_path,
-                                               const uint16_t team_number,
-                                               std::string_view channel_name)
+  ConstantSender(aos::EventLoop *event_loop, std::string constants_path,
+                 const uint16_t team_number, std::string_view channel_name)
       : team_number_(team_number),
         channel_name_(channel_name),
         constants_path_(constants_path),