[tidy] modernize-deprecated-headers

platform/glfw/main.cpp

@@ -7,7 +7,7 @@
 #include <mbgl/util/default_thread_pool.hpp>
 #include <mbgl/storage/default_file_source.hpp>
 
-#include <signal.h>
+#include <csignal>
 #include <getopt.h>
 #include <fstream>
 #include <sstream>

test/storage/local_file_source.test.cpp

@@ -3,7 +3,7 @@
 #include <mbgl/util/run_loop.hpp>
 
 #include <unistd.h>
-#include <limits.h>
+#include <climits>
 #include <gtest/gtest.h>
 
 namespace {

test/util/memory.test.cpp

@@ -17,7 +17,7 @@
 #include <unordered_map>
 #include <utility>
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <unistd.h>
 
 using namespace mbgl;