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/third_party/gflags/bazel/gflags.bzl b/third_party/gflags/bazel/gflags.bzl
index df34e4e..bfa006e 100644
--- a/third_party/gflags/bazel/gflags.bzl
+++ b/third_party/gflags/bazel/gflags.bzl
@@ -74,6 +74,7 @@
         "-DHAVE_STRTOQ",
         "-DHAVE_RWLOCK",
         "-Wno-format-nonliteral",
+        "-Wno-cast-function-type",
     ] + select({
         "//:x64_windows": [
             "-DOS_WINDOWS",