Frameworks/base: Turn on -Wall -Werror in cmds

Fix small warnings, turn on -Wall -Werror.

Change-Id: Iab1f01a7c7ebd6ba832b75067c5e395f380a1b8b
diff --git a/cmds/backup/Android.mk b/cmds/backup/Android.mk
index 42e5133..8e1508c 100644
--- a/cmds/backup/Android.mk
+++ b/cmds/backup/Android.mk
@@ -12,4 +12,6 @@
 LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
 LOCAL_MODULE_TAGS := optional
 
+LOCAL_CFLAGS += -Wall -Werror -Wunused -Wunreachable-code
+
 include $(BUILD_EXECUTABLE)