bootstat: Add reboot,userrequested

Result of holding power button down and hitting restart.

Test: compile
Bug: 63736262
Change-Id: I271bdf135cece5fd9dc9e60ddf8add595ed3da4c
diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index e2202fd..7c0b15e 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -203,6 +203,7 @@
     {"reboot,", 65},
     {"reboot,shell", 66},
     {"reboot,adb", 67},
+    {"reboot,userrequested", 68},
 };
 
 // Converts a string value representing the reason the system booted to an