Fix undefined reference to `yywrap'.

diff --git a/lexxer.l b/lexxer.l
index 9725d0b..15264bc 100644
--- a/lexxer.l
+++ b/lexxer.l
@@ -1,4 +1,5 @@
 %option nounput
+%option noyywrap
 
 %k 10000
 %n 5000
