Add the missing LOCAL_CFLAGS for librecovery.

The -DAB_OTA_UDPATER part was missing when separating the librecovery
module (commit 62e0bc7586).

Bug: 37300957
Test: Build sailfish recovery image and sideload full OTA.
Change-Id: Idd25662f6bc812c1aca95b096802f59b051f8d63
(cherry picked from commit 25dbe1717e)

Android.mk

@@ -47,6 +47,11 @@ LOCAL_SRC_FILES := \
     install.cpp
 LOCAL_CFLAGS := -Wno-unused-parameter -Werror
 LOCAL_CFLAGS += -DRECOVERY_API_VERSION=$(RECOVERY_API_VERSION)
+
+ifeq ($(AB_OTA_UPDATER),true)
+    LOCAL_CFLAGS += -DAB_OTA_UPDATER=1
+endif
+
 LOCAL_MODULE := librecovery
 LOCAL_STATIC_LIBRARIES := \
     libminui \