set zero shutdown timeout for eng build

- still it will take time to kill services, < 3 secs in tested device.

bug: 36678028
Test: reboot

(cherry picked from commit 56425ed87e1ad7c63437d67c3b17ed7e2ba8d340)

Change-Id: I75b5843b08cdcdbf67c4fe500aa0dd7302dd44d7

init/Android.mk

@@ -16,6 +16,14 @@ init_options += \
     -DREBOOT_BOOTLOADER_ON_PANIC=0
 endif
 
+ifneq (,$(filter eng,$(TARGET_BUILD_VARIANT)))
+init_options += \
+    -DSHUTDOWN_ZERO_TIMEOUT=1
+else
+init_options += \
+    -DSHUTDOWN_ZERO_TIMEOUT=0
+endif
+
 init_options += -DLOG_UEVENTS=0
 
 init_cflags += \

init/reboot.cpp

@@ -341,7 +341,14 @@ void DoReboot(unsigned int cmd, const std::string& reason, const std::string& re
     }
 
     /* TODO update default waiting time based on usage data */
-    unsigned int shutdownTimeout = android::base::GetUintProperty("ro.build.shutdown_timeout", 10u);
+    constexpr unsigned int shutdownTimeoutDefault = 10;
+    unsigned int shutdownTimeout = shutdownTimeoutDefault;
+    if (SHUTDOWN_ZERO_TIMEOUT) {  // eng build
+        shutdownTimeout = 0;
+    } else {
+        shutdownTimeout =
+            android::base::GetUintProperty("ro.build.shutdown_timeout", shutdownTimeoutDefault);
+    }
     LOG(INFO) << "Shutdown timeout: " << shutdownTimeout;
 
     static const constexpr char* shutdown_critical_services[] = {"vold", "watchdogd"};