Fix warnings and set Werror flags to not let them happen again.

Test: it builds.
Bug: b/37159108
Change-Id: I3b0d6376d81615774b60e71a6eebf6f38224df88
diff --git a/libril/Android.mk b/libril/Android.mk
index 8d7fe8d..e12dcf0 100644
--- a/libril/Android.mk
+++ b/libril/Android.mk
@@ -26,7 +26,7 @@
     libprotobuf-c-nano-enable_malloc \
 
 #LOCAL_CFLAGS := -DANDROID_MULTI_SIM -DDSDA_RILD1
-LOCAL_CFLAGS += -Wno-unused-parameter
+LOCAL_CFLAGS += -Wall -Wextra -Wno-unused-parameter -Werror
 
 ifeq ($(SIM_COUNT), 2)
     LOCAL_CFLAGS += -DANDROID_SIM_COUNT_2