Adding support for quiescent reboot to recovery

Bug: 37401320
Test: build and push OTA and hit adb reboot recovery,quiescent. The screen should remain off throughout the upgrade process.
Change-Id: Ibed3795c09e26c4fa73684d40b94e40c78394d3f
diff --git a/common.h b/common.h
index bda7935..62fb132 100644
--- a/common.h
+++ b/common.h
@@ -43,4 +43,6 @@
 
 bool is_ro_debuggable();
 
+bool reboot(const std::string& command);
+
 #endif  // RECOVERY_COMMON_H