Turn on -Werror for recovery

Also remove the 0xff comparison when validating the bootloader
message fields. As the fields won't be erased to 0xff after we
remove the MTD support.

Bug: 28202046
Test: The recovery folder compiles for aosp_x86-eng
Change-Id: Ibb30ea1b2b28676fb08c7e92a1e5f7b6ef3247ab
diff --git a/uncrypt/Android.mk b/uncrypt/Android.mk
index 09cfdfc..3613799 100644
--- a/uncrypt/Android.mk
+++ b/uncrypt/Android.mk
@@ -19,23 +19,24 @@
 LOCAL_SRC_FILES := bootloader_message_writer.cpp
 LOCAL_MODULE := libbootloader_message_writer
 LOCAL_STATIC_LIBRARIES := libbase libfs_mgr
+LOCAL_CFLAGS := -Werror
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/..
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
 
 LOCAL_CLANG := true
-
 LOCAL_SRC_FILES := uncrypt.cpp
-
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/..
-
 LOCAL_MODULE := uncrypt
-
-LOCAL_STATIC_LIBRARIES := libbootloader_message_writer libbase \
-                          liblog libfs_mgr libcutils \
-
+LOCAL_STATIC_LIBRARIES := libbootloader_message_writer \
+                          libbase \
+                          liblog \
+                          libfs_mgr \
+                          libcutils
+LOCAL_CFLAGS := -Werror
 LOCAL_INIT_RC := uncrypt.rc
 
 include $(BUILD_EXECUTABLE)