Merge "Adding include to functional" into main am: b0f9c07590

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2679741

Change-Id: Ia2332c046edaa70bb79bd208cb16a6cdb9423e25
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/fastboot/fastboot.h b/fastboot/fastboot.h
index f6ffb64..dc57149 100644
--- a/fastboot/fastboot.h
+++ b/fastboot/fastboot.h
@@ -27,6 +27,7 @@
  */
 #pragma once
 
+#include <functional>
 #include <string>
 #include "fastboot_driver.h"
 #include "fastboot_driver_interface.h"