libc: fix fstatfs() implementation.

The syscall expects the size of the buffer as the second argument.

Change-Id: I99ede2fec7fcd385ca03ff022c2cffa4297bea8d
diff --git a/libc/Android.mk b/libc/Android.mk
index 80c8cc7..6b9a904 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -14,6 +14,7 @@
 	unistd/exec.c \
 	unistd/fcntl.c \
 	unistd/fnmatch.c \
+	unistd/fstatfs.c \
 	unistd/ftime.c \
 	unistd/ftok.c \
 	unistd/getcwd.c \