awk: prn returns nil.

* stdlib/awk.tl (awk-state prn): Return nil in the no-argument
case instead of returning whatever put-string returns.

* tests/015/awk-misc.tl: New file.

* txr.1: Documented.

1 files changed, 10 insertions, 0 deletions

diff --git a/tests/015/awk-misc.tl b/tests/015/awk-misc.tl
new file mode 100644
index 00000000..af61857d
--- /dev/null
+++ b/tests/015/awk-misc.tl
@@ -0,0 +1,10 @@
+(load "../common")
+
+(let ((*stdout* *stdnull*))
+  (test
+    (build
+      (awk
+        (:inputs '(""))
+        (t (add (prn 1 2 3))
+           (add (prn)))))
+    (nil nil)))