Build tzcode with hidden visibility.

Bug: 11156955
Change-Id: Ib98d837b56cbbdfd01687cb3054fe3103eec0da9
diff --git a/libc/Android.mk b/libc/Android.mk
index 4ed9468..a6298a0 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -585,7 +585,10 @@
 # tzcode doesn't include wcsftime, so we use the OpenBSD one.
 LOCAL_SRC_FILES += upstream-openbsd/lib/libc/time/wcsftime.c
 
-LOCAL_CFLAGS := $(libc_common_cflags)
+LOCAL_CFLAGS := $(libc_common_cflags) \
+    -fvisibility=hidden \
+    -Werror \
+
 # Don't use ridiculous amounts of stack.
 LOCAL_CFLAGS += -DALL_STATE
 # Include tzsetwall, timelocal, timegm, time2posix, and posix2time.
@@ -597,7 +600,7 @@
 # Include timezone and daylight globals.
 LOCAL_CFLAGS += -DUSG_COMPAT=1
 LOCAL_CFLAGS += -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
-LOCAL_CFLAGS += -Dlint -Werror
+LOCAL_CFLAGS += -Dlint
 
 LOCAL_CONLYFLAGS := $(libc_common_conlyflags)
 LOCAL_CPPFLAGS := $(libc_common_cppflags)