Use TARGET_RECOVERY_PRE_COMMAND before calling __reboot() recovery

For the Power menu,
frameworks/base/core/jni/android_os_Power.cpp#L180
already uses TARGET_RECOVERY_PRE_COMMAND if
TARGET_RECOVERY_PRE_COMMAND is defined in the
BoardConfig.mk for a device to make a system() call before
calling __reboot() for recovery. This commit adds
the same thing to the other places that we know we are
getting into recovery using __reboot().

Change-Id: Ifd0394fed1e87b63d80d95e0e2a049004518e27e
diff --git a/Android.mk b/Android.mk
index 2d7db14..eccce6b 100644
--- a/Android.mk
+++ b/Android.mk
@@ -31,7 +31,7 @@
 RECOVERY_API_VERSION := 2
 LOCAL_CFLAGS += -DRECOVERY_API_VERSION=$(RECOVERY_API_VERSION)
 
-BOARD_RECOVERY_DEFINES := BOARD_HAS_NO_SELECT_BUTTON BOARD_HAS_SMALL_RECOVERY BOARD_LDPI_RECOVERY BOARD_UMS_LUNFILE
+BOARD_RECOVERY_DEFINES := BOARD_HAS_NO_SELECT_BUTTON BOARD_HAS_SMALL_RECOVERY BOARD_LDPI_RECOVERY BOARD_UMS_LUNFILE TARGET_RECOVERY_PRE_COMMAND
 
 $(foreach board_define,$(BOARD_RECOVERY_DEFINES), \
   $(if $($(board_define)), \