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/tests/Android.mk b/tests/Android.mk
index 633b3c4..0754c7a 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -19,6 +19,7 @@
 # Unit tests
 include $(CLEAR_VARS)
 LOCAL_CLANG := true
+LOCAL_CFLAGS := -Werror
 LOCAL_MODULE := recovery_unit_test
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_STATIC_LIBRARIES := \
@@ -35,7 +36,7 @@
 # Component tests
 include $(CLEAR_VARS)
 LOCAL_CLANG := true
-LOCAL_CFLAGS += -Wno-unused-parameter
+LOCAL_CFLAGS += -Wno-unused-parameter -Werror
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_MODULE := recovery_component_test
 LOCAL_C_INCLUDES := bootable/recovery