add fortified memchr/memrchr implementations

Change-Id: I38c473cc0c608b08f971409a95eb8b853cb2ba1c
diff --git a/libc/Android.mk b/libc/Android.mk
index 9d3b62a..6256caf 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -69,7 +69,9 @@
 libc_common_src_files += \
     bionic/__FD_chk.cpp \
     bionic/__fgets_chk.cpp \
+    bionic/__memchr_chk.cpp \
     bionic/__memmove_chk.cpp \
+    bionic/__memrchr_chk.cpp \
     bionic/__poll_chk.cpp \
     bionic/__pread64_chk.cpp \
     bionic/__pread_chk.cpp \