add notice about where devurandom.c is from

diff --git a/devurandom.c b/devurandom.c
index 8a7a7b6..bd6ba2e 100644 (file)
--- a/devurandom.c
+++ b/devurandom.c
@@ -1,3 +1,5 @@
+// copied from NaCl (the crypto lib)
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>