Check alpha-sorting of includes during presubmit.

src/platform-macos.cc

Index: src/platform-macos.cc
diff --git a/src/platform-macos.cc b/src/platform-macos.cc
index 4301875b9b61b77e8f4bdf5972e3870b90e99ede..dfff0d17efdb1488077283cadb03d970e371088f 100644
--- a/src/platform-macos.cc
+++ b/src/platform-macos.cc
@@ -6,30 +6,30 @@
 // parts, the implementation is in platform-posix.cc.
 
 #include <dlfcn.h>
-#include <unistd.h>
-#include <sys/mman.h>
 #include <mach/mach_init.h>
 #include <mach-o/dyld.h>
 #include <mach-o/getsect.h>
+#include <sys/mman.h>
+#include <unistd.h>
 
 #include <AvailabilityMacros.h>
 
-#include <pthread.h>
-#include <semaphore.h>
-#include <signal.h>
+#include <errno.h>
 #include <libkern/OSAtomic.h>
 #include <mach/mach.h>
 #include <mach/semaphore.h>
 #include <mach/task.h>
 #include <mach/vm_statistics.h>
-#include <sys/time.h>
-#include <sys/resource.h>
-#include <sys/types.h>
-#include <sys/sysctl.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <signal.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
-#include <errno.h>
+#include <sys/resource.h>
+#include <sys/sysctl.h>
+#include <sys/time.h>
+#include <sys/types.h>
 
 #undef MAP_TYPE