Clang Tidy fixes

Change-Id: I51429acbf2a7b81605a2fd03a6b7c10317984674

examples/nist.cc

diff --git a/examples/nist.cc b/examples/nist.cc
index d95e12c..a768b42 100644
--- a/examples/nist.cc
+++ b/examples/nist.cc
@@ -71,9 +71,12 @@
 // Average LRE     2.3      4.3       4.0  6.8      4.4    9.4
 //      Winner       0        0         5   11        2     41
 
+#include <cstdlib>
 #include <fstream>
 #include <iostream>
 #include <iterator>
+#include <string>
+#include <vector>
 
 #include "Eigen/Core"
 #include "ceres/ceres.h"

internal/ceres/array_utils.cc

diff --git a/internal/ceres/array_utils.cc b/internal/ceres/array_utils.cc
index 3247ba9..b2565c4 100644
--- a/internal/ceres/array_utils.cc
+++ b/internal/ceres/array_utils.cc
@@ -74,7 +74,9 @@
   }
 }
 
-void AppendArrayToString(const int64_t size, const double* x, std::string* result) {
+void AppendArrayToString(const int64_t size,
+                         const double* x,
+                         std::string* result) {
   for (int64_t i = 0; i < size; ++i) {
     if (x == nullptr) {
       StringAppendF(result, "Not Computed  ");

internal/ceres/rotation_test.cc

diff --git a/internal/ceres/rotation_test.cc b/internal/ceres/rotation_test.cc
index c5a2016..f677759 100644
--- a/internal/ceres/rotation_test.cc
+++ b/internal/ceres/rotation_test.cc
@@ -36,6 +36,7 @@
 #include <limits>
 #include <random>
 #include <string>
+#include <utility>
 
 #include "ceres/constants.h"
 #include "ceres/internal/eigen.h"