add a fortified implementation of getcwd

Change-Id: Ice3e6d3e1ff07788305dc85f8ee4059baad5fac4
diff --git a/libc/Android.mk b/libc/Android.mk
index 2f0c723..0f18ca4 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -72,6 +72,7 @@
     bionic/__fgets_chk.cpp \
     bionic/__fread_chk.cpp \
     bionic/__fwrite_chk.cpp \
+    bionic/__getcwd_chk.cpp \
     bionic/__memchr_chk.cpp \
     bionic/__memmove_chk.cpp \
     bionic/__memrchr_chk.cpp \