Ascii formatter: do not complain about port text.

The ascii formatter already was happy to read ports in the form
"42/tcp"; however it emitted a warning message for each line.

This patch fixes this and adds a bit more testing for the existing
behavior.

testing/btest/scripts/base/frameworks/input/port-embedded.bro

@@ -0,0 +1,44 @@
+# @TEST-EXEC: btest-bg-run bro bro -b %INPUT
+# @TEST-EXEC: btest-bg-wait 10
+# @TEST-EXEC: btest-diff bro/.stdout
+# @TEST-EXEC: btest-diff bro/.stderr
+
+@TEST-START-FILE input.log
+#fields	i	p
+1.2.3.4	80/tcp
+1.2.3.5	52/udp
+1.2.3.6	30/unknown
+1.2.3.7	50/trash
+@TEST-END-FILE
+
+redef exit_only_after_terminate = T;
+
+redef InputAscii::empty_field = "EMPTY";
+
+module A;
+
+type Idx: record {
+	i: addr;
+};
+
+type Val: record {
+	p: port;
+};
+
+global servers: table[addr] of Val = table();
+
+event line(description: Input::TableDescription, tpe: Input::Event, left: Idx, right: Val)
+	{
+	print left, right;
+	}
+
+event bro_init()
+	{
+	Input::add_table([$source="../input.log", $name="input", $idx=Idx, $val=Val, $ev=line, $destination=servers]);
+	}
+
+event Input::end_of_data(name: string, source: string)
+	{
+	Input::remove("input");
+	terminate();
+	}