Add missing #include of <limits> for loss functions.

Change-Id: Id632451429e03031a1533a9be795270debc70706
diff --git a/internal/ceres/loss_function.cc b/internal/ceres/loss_function.cc
index 4ad01e3..62b545b 100644
--- a/internal/ceres/loss_function.cc
+++ b/internal/ceres/loss_function.cc
@@ -34,6 +34,7 @@
 
 #include <cmath>
 #include <cstddef>
+#include <limits>
 
 namespace ceres {