Update .gitignore with auto-generated lex/yacc outputs

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/.gitignore b/.gitignore
index 3993a30..c9d90fb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,5 @@
 /config.log
 /cscope.out
 /fio
+y.tab.*
+lex.yy.c