Move over to ABSL logging and flags.

Removes gperftools too since that wants gflags.

Here come the fireworks.

Change-Id: I79cb7bcf60f1047fbfa28bfffc21a0fd692e4b1c
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/y2018/control_loops/python/2d_plot.cc b/y2018/control_loops/python/2d_plot.cc
index 1d2a686..c65bae6 100644
--- a/y2018/control_loops/python/2d_plot.cc
+++ b/y2018/control_loops/python/2d_plot.cc
@@ -2,17 +2,18 @@
 #include <cmath>
 #include <thread>
 
-#include "gflags/gflags.h"
+#include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
 #include "third_party/matplotlib-cpp/matplotlibcpp.h"
 
-DEFINE_double(yrange, 1.0, "+- y max");
+ABSL_FLAG(double, yrange, 1.0, "+- y max");
 
 double fx(double x, double yrange) {
   return 2.0 * ((1.0 / (1.0 + ::std::exp(-x * 2.0 / yrange)) - 0.5)) * yrange;
 }
 
 int main(int argc, char **argv) {
-  gflags::ParseCommandLineFlags(&argc, &argv, false);
+  absl::ParseCommandLine(argc, argv);
 
   matplotlibcpp::figure();
   ::std::vector<double> x;
@@ -21,10 +22,10 @@
 
   for (double i = -5.0; i < 5.0; i += 0.01) {
     x.push_back(i);
-    y.push_back(fx(i, FLAGS_yrange));
-    slope_y.push_back(
-        (fx(i + 0.0001, FLAGS_yrange) - fx(i - 0.0001, FLAGS_yrange)) /
-        (2.0 * 0.0001));
+    y.push_back(fx(i, absl::GetFlag(FLAGS_yrange)));
+    slope_y.push_back((fx(i + 0.0001, absl::GetFlag(FLAGS_yrange)) -
+                       fx(i - 0.0001, absl::GetFlag(FLAGS_yrange))) /
+                      (2.0 * 0.0001));
   }
 
   matplotlibcpp::plot(x, y, {{"label", "saturated x"}});